ID: NCC-240821-001 Letter_WMI for Foreign Built Vehicles-Ford-565_Final

September 11, 2024

Ms. Emily Frascaroli 

Ford Motor Company 

330 Town Center Drive 

Dearborn, MI 48126-2738 

Dear Ms. Frascaroli:

This responds to your August 9, 2022 letter asking about the National Highway Traffic Safety Administration’s (NHTSA’s) requirements regarding the characters in vehicle identification numbers (VINs) that identify the manufacturer. These characters are commonly referred to as the World Manufacturer Identifier (WMI). You ask whether Ford Motor Company (Ford) may use one of its U.S.-assigned WMIs in the VINs of vehicles Ford manufacturers outside of the United States for importation into and sale in the United States. The answer is yes. 

For the benefit of the public and to clarify NHTSA’s position on WMI requirements more generally, this letter also rescinds a previous interpretation on a similar issue. In a November 3, 2000 letter to Mr. Karl-Heinz Ziwica of BMW of North America, NHTSA addressed the use of a German-issued WMI in the VIN of a vehicle assembled in the United States. Because we believe the two issues are related, this letter also includes a discussion of that letter and NHTSA’s decision to rescind it. 

In responding to this request, NHTSA notes that the contents of this letter do not have the force and effect of law and are not meant to bind the public in any way. This letter is only intended to provide clarity regarding existing requirements under the law at the time of signature.

Facts Presented 

In your letter, you explain that Ford was evaluating plans to manufacture vehicles in another country (“Country X”) that will be sold in the United States. Your letter states that this manufacturing would be done through a 50/50 joint venture. The vehicles, you state, would be classified as multipurpose passenger vehicles (MPVs) under 49 CFR § 571.3. As you explain, Country X has assigned Ford a WMI for passenger cars and a WMI for light trucks. However, because Country X’s regulations do not recognize the classification of a vehicle as an MPV, you state that it will not assign Ford a WMI for this type of vehicle. Instead, the WMI-issuing authority in Country X has suggested that Ford use the WMI it issued to Ford for “passenger car” types.1 You explain that this solution could complicate VIN assignment in the future if Ford later decides to also manufacture passenger cars in Country X for sale in the United States. Specifically, because NHTSA requires a WMI to uniquely identify both manufacturer and vehicle type, Ford cannot use a single WMI for both MPVs and passenger cars. See 49 CFR§ 565.15(a). To avoid this possible complication, you ask whether Ford may use a U.S.-assigned WMI that identifies Ford as the manufacturer and MPV as the vehicle type for the MPVs manufactured in Country X for the U.S. market. You state that this approach would not obscure that the vehicle was manufactured in Country X because the manufacturing location in Country X will be noted in position eleven (11) of the VIN. 

Background and Relevant Provisions 

The VIN is the cornerstone of NHTSA’s safety defect and standard noncompliance recall program.2 NHTSA’s VIN requirements must ensure effective identification of vehicles and vehicle manufacturers. To this end, NHTSA established a 17-character VIN system, whose requirements are found at 49 CFR Part 565. This system requires manufacturers to assign VINs that meet certain formatting requirements and have certain information encoded into them.
NHTSA also requires manufacturers to submit deciphering information that allows the agency to decode the information in the VINs.3 

NHTSA’s VIN regulation requires that “[e]ach vehicle manufactured in one stage shall have a VIN that is assigned by the manufacturer.”4 For large-volume manufacturers, the first three characters of a VIN serve as the manufacturer identifier, which is commonly referred to as the WMI.5 The manufacturer identifier uniquely identifies the manufacturer and the type of motor vehicle.6 These characters are assigned in accordance with section 565.16(a) of the VIN regulation, which states that NHTSA “has contracted with SAE International to coordinate the assignment of manufacturer identifiers to manufacturers in the United States.” Section 565.16(a), however, does not address the assignment of WMIs to manufacturers located outside of the United States. Instead, those WMIs are typically issued by WMI-issuing entities in the country in which the manufacturer is located.

The WMI system depends on international cooperation, which is facilitated by SAE International and the use of ISO 3780, an international standard that sets forth general specifications for WMIs and explains how the issuance of WMIs will be coordinated at the international level. This international cooperation is necessary to ensure that two countries do not issue the same WMI. In addition to serving as NHTSA’s contractor for the purpose of issuing WMIs to U.S. manufacturers, SAE International also coordinates WMIs on an international level, by

1 According to your letter, the vehicles at issue would be considered “passenger cars” in Country X.
2 Final rule amending NHTSA’s VIN requirements, 44 FR 17489, 17490 (Mar. 22, 1979).
3 See 49 CFR § 565.16(c).
4 49 CFR § 565.13(a).
5 If the manufacturer is a low-volume manufacturer, the manufacturer identifier is six characters. 49 CFR § 565.15(a).
6 See 49 CFR § 565.15(a).

coordinating the assignment of ranges of WMIs to countries, as well as by keeping a repository of assigned WMIs. Ranges of WMIs are assigned based on the first and second characters of a WMI, with the first character generally identifying a particular geographic area, and the second character identifying a particular country within the geographic area (e.g., a WMI with the first character of S through Z indicates Europe, and WMIs beginning with ZA to ZU are assigned to Italy). The WMI-issuing authorities in each country then assign WMIs to individual manufacturers. 

Discussion

Your situation presents a new issue for NHTSA to consider. To respond to your request, we will address two issues: (1) whether Ford is the manufacturer of the vehicles at issue for the purposes of being identified by the WMI in the VIN of the vehicles at issue; and (2) whether NHTSA requires the WMI to indicate the country of manufacture, either by being issued in the country of manufacture or by otherwise identifying the country of manufacture. 

Manufacturer Identified by the WMI 

We will first consider whether Ford may be identified as the manufacturer of the vehicles produced by the 50/50 joint venture in Country X, or whether the company that actually builds the vehicles must be identified as the manufacturer in the WMI. Although your letter did not ask this question, it is a threshold question for your inquiry. One of the key requirements for the WMI, found at section 565.15(a) of the VIN regulation, is that it must uniquely identify the manufacturer. Therefore, we will first address whether one of Ford’s WMIs may be used in the VINs of the subject vehicles. While Ford may not be the assembler of the vehicles,7 NHTSA believes that the 50/50 joint venture may still allow Ford to “control” production of the vehicles sufficiently to be designated as the manufacturer for WMI purposes.8 

For purposes of assigning VINs, NHTSA interprets the requirement for the WMI to identify the manufacturer to mean that the WMI must identify the manufacturer that certifies the vehicle under 49 CFR Part 567, NHTSA’s certification regulation. The VIN’s primary purpose is to facilitate the identification of vehicles and the manufacturers responsible for those vehicles. Therefore, it would be inconsistent to allow different entities to be identified on the certification 

7 As Ford explained, the vehicles will be manufactured by the 50/50 joint venture.
8 Additionally, Ford could not be considered the “manufacturer” for WMI purposes based on its being the vehicle’s importer because 49 CFR § 565.14(a) states that importers must use the VIN “assigned by the original manufacturer of the motor vehicle.” Accordingly, even though 49 CFR § 565.12(b) defines a manufacturer as including a person “importing motor vehicles or motor vehicle equipment for resale,” consistent with the Safety Act’s definition of “manufacturer” at 49 U.S.C. § 30102(a)(6), NHTSA does not consider importers to be manufacturers for purposes of VIN assignment. Rather, NHTSA only considers entities that are “manufacturing or assembling motor vehicles,” id. § 30102(a)(6)(A), to be manufacturers for purposes of the WMI.

label and in the VIN.9 This reading is consistent with ISO 3780,10 and with a past NHTSA interpretation in which Volkswagen asked which WMI should be used when vehicle assembly is carried out by one company on behalf of another.11 In that interpretation, NHTSA stated that the WMI of the company under whose authority the assembly is carried out and which maintains responsibility for the vehicle’s compliance with safety standards should be used.12 NHTSA continues to believe this is the most appropriate reading of the regulation. 

The next question is which manufacturer in a joint venture would certify the vehicle, which would also determine which manufacturer’s WMI should be used in the VIN. Typically, under 49 CFR § 567, the name of the actual assembler must appear on the certification label. This requirement reflects that the purpose of the manufacturer’s designation in the certification regulations is to identify the entity that has “primary technical responsibility for conformity of the design and quality control of the assembly.”13 

However, NHTSA also explicitly permits other entities to assume responsibility for motor vehicles’ compliance and to make certifications to that effect. Accordingly, if a vehicle is assembled by a corporation that is controlled by another corporation that assumes responsibility for conformity with the standards, the name of that controlling corporation may be used on the certification label.14 

In a 1981 letter to Paccar Inc. (Paccar), NHTSA considered how this certification standard would apply where an entity owned a partial percent interest in a motor vehicle assembler.15 We believe the analysis in that letter is relevant to determining whether Ford is in “control” of the assembler of the vehicles at issue. In the Paccar letter, NHTSA concluded that Paccar could be identified as the manufacturer on the certification label for vehicles assembled by Kenworth Mexicana, a Mexican affiliate. NHTSA observed that even though Paccar owned only a 49

9 We note that for vehicles built in more than one stage, the VIN must be assigned by the incomplete vehicle manufacturer and the incomplete vehicle manufacturer, any intermediate vehicle manufacturers, and the final stage manufacturer each have certification responsibilities.
10 In its 2008 final rule amending its VIN regulations, NHTSA stated that when issuing identifiers to U.S. manufacturers, SAE also ensures that the identifiers comply with the specifications in ISO Standard 3780. See 73 FR 23367, 23369 (Apr. 30, 2008). In specifying requirements for WMIs, ISO 3780:2009 references the definition of “manufacturer” found in ISO Standard 3779. Section 3.5 of ISO Standard 3779:2009 in turn defines manufacturer as the “person, firm, or corporation that issues the certificate of conformity or that demonstrates compliance and assumes product liability for a vehicle ready for operation, independent of the location of the assembly plant.”
11 See Letter to Volkswagen of America Inc. (November 20, 1978), available at https://www.nhtsa.gov/interpretations/aiam2885.
12 While this 1978 interpretation has been superseded in part, NHTSA has not reconsidered its conclusion that the WMI should identify the certifying manufacturer.
13 See Letter to Kawasaki Motors Corporation (August 15, 1969), available at https://www.nhtsa.gov/interpretations/nht69-228.
14 See 49 CFR § 567.4(g)(1)(i). As NHTSA explained in its 1969 final rule on Part 567, this exception was adopted in recognition of the fact that, “particularly in some foreign countries, assembly of a vehicle may be performed by a subsidiary corporation controlled by a parent that is the generally known ‘nameplate company.’” The agency determined that in such a situation, “no important purpose is served by requiring the name of a lesser-known subsidiary corporation on the label.” 34 FR 11360 (Jul. 9, 1969).
15 The letter is available at https://www.nhtsa.gov/interpretations/nht81-326.

percent interest in Kenworth Mexicana, it was responsible for the design of the vehicles produced in Mexico and exercised control over all matters relating to their compliance with safety standards. In this circumstance, the letter concluded that Paccar’s name could appear on the certification label and noted that allowing Paccar to be identified as the manufacturer was consistent with the reasons the agency had adopted the controlling corporation exception to the requirement that the vehicle assembler’s name must appear on the certification label.16 

The reasoning in the Paccar letter applies to joint ventures as well. We believe that the ownership interest and the entity’s involvement in the vehicles’ design, production, and compliance—not the particular corporate structure—are the most relevant factors for determining “control.” Accordingly, we conclude that a partner owning 50 percent of a joint venture that is also responsible for a vehicle’s design and exercises control over all matters relating to its compliance with safety standards may be identified as the manufacturer for purposes of Part 567. Therefore, if Ford meets these requirements, Ford may be identified as the manufacturer on the certification labels of the subject vehicles even though Ford is not the actual assembler of the vehicles. Moreover, if Ford is the manufacturer on the certification labels, then Ford may also be the manufacturer for purposes of the VIN’s WMI. 

Thus, based on the facts presented, and assuming that Ford would be permitted to certify the vehicles pursuant to Part 567, NHTSA would conclude that the vehicles produced through Ford’s joint venture in Country X may have VINs that are assigned by Ford and contain a WMI assigned to Ford. 

Country of Manufacture 

The second part of the analysis considers whether the WMI must indicate the country of manufacture either by (1) being issued by the country in which the vehicle was manufactured or (2) otherwise identifying the country of manufacture. We find that the answer is no: Part 565 does not require this.

NHTSA’s VIN regulation is silent as to whether the WMI must indicate the country of manufacture. Since NHTSA regulations do not prohibit the use of a U.S.-assigned WMI in VINs of vehicles manufactured in Country X for sale in the United States, such practice is permissible under the circumstances described in this letter.17

16 Relatedly, other NHTSA interpretations have held that vehicles manufactured under contract may not be certified by the entity that assumes responsibility for the compliance of those vehicles unless that entity has an ownership interest in the assembler. See Letter to Howard A. Silverman (November 11, 2000), available at https://www.nhtsa.gov/interpretations/gm3crs; Letter to Mr. Larry Smith (January 15, 2002), available at https://www.nhtsa.gov/interpretations/londontaxi2.
17 We also note that in the 2008 final rule that amended Part 565, we stated that, to comply with ISO 3780, the first three digits of a VIN “must also indicate the country in which the vehicle was manufactured.” 73 FR 23367, 23369 (Apr. 30, 2008). However, ISO 3780 has always specified that WMIs are assigned by the WMI-issuing entity in the country in which the manufacturer is headquartered, not that WMIs must indicate the country in which the vehicle was manufactured. Similarly, the BMW interpretation letter discussed below, which we are now rescinding, indicated in a footnote that German-issued WMIs did not conform to SAE’s WMI format for U.S.-manufactured

Based on the information you provided, and assuming that Ford would be permitted to certify the vehicles and in fact does so, NHTSA’s regulations would not prohibit Ford from using one of its U.S.-assigned WMIs for vehicles produced in Country X through Ford’s 50/50 joint venture.
However, as explained above, if Ford did not certify the vehicles, NHTSA would not consider it appropriate for a Ford WMI to be used. 

Further, while NHTSA still believes that knowing the vehicle’s location of manufacture is important for NHTSA’s enforcement purposes, the WMI alone is not necessary to serve this function. NHTSA requires manufacturers to code information about plant of manufacture into position 11 of the VIN, thus providing more detailed information about where the vehicle was produced.18 

BMW Interpretation 

As mentioned above, your letter presented a new issue to consider. However, in considering that issue, we identified prior guidance that now requires updating. In an interpretation dated November 3, 2000, that we issued to Mr. Karl-Heinz Ziwica of BMW of North America, we addressed the use of a German-issued WMI on a motor vehicle assembled in the United States. BMW had been using German-issued WMIs on vehicles manufactured at its plant in Greer, South Carolina. We concluded that the VINs of vehicles produced at the Greer plant must bear WMIs assigned or approved by NHTSA or its contractor. We now rescind that interpretation to ensure consistent guidance. 

The BMW letter relied on an earlier version of what is now section 565.16(a) of the VIN regulation. The previous version was found at 49 CFR § 565.7(a) and was similar though not identical to the current rule. The BMW letter interpreted the provision then-section 565.7(a) as requiring the vehicles at issue, which had been manufactured in the United States, to have VINs with WMIs that had been assigned or approved by NHTSA. However, Part 565 was subsequently updated in 2008. The updated, recodified version of what is now section 565.16(a) clarified that the provision simply provides an explanation of a process and does not itself create any substantive requirements. The rule does not provide that NHTSA must assign or approve WMIs; rather, it simply observes that NHTSA contracts with SAE to assign WMIs. 

If we were to consider BMW’s request today, we would find that there is no requirement in Part 565 that prohibits the use of non-U.S. WMIs on vehicles produced in the United States. As discussed above, the WMI must uniquely identify the certifying manufacturer and the vehicle type. Kraftfahrt Bundesamt is the WMI-issuing authority for Germany and fulfills a similar role 

vehicles because the WMIs in the subject VINs did not fall within the range that would indicate that the WMI had been assigned by the United States. See Letter to Mr. Karl-Heinz Ziwica (November 3, 2000), available at https://www.nhtsa.gov/interpretations/21915drn. With this interpretation and the rescission of the BMW letter, NHTSA’s requirements for WMIs will be more consistent with ISO 3780. Nonetheless, we also note that NHTSA’s requirements are still not in complete alignment with ISO 3780 because NHTSA does not require WMIs to be issued in the country in which the manufacturer is headquartered.
18 49 CFR § 565.15(d)(2).

to the one SAE International fulfills under its contract with NHTSA to assign WMIs to U.S. manufacturers. Because NHTSA does not require vehicles manufactured in the United States to have VINs that include a U.S.-assigned WMI, NHTSA now concludes that it would be permissible for BMW to use German-issued WMIs on vehicles produced in the United States by a BMW subsidiary that are certified by the BMW parent company headquartered in Germany. 

Conclusion 

As discussed above, NHTSA’s regulations do not prohibit the use of a U.S.-issued WMI in the VINs of vehicles manufactured outside of the United States for importation into and sale in the United States. Accordingly, assuming Ford may be identified as the manufacturer on the certification labels of the subject vehicles manufactured in Country X, we believe it would be permissible for Ford’s U.S.-issued WMI for MPVs to be incorporated into the VINs affixed to those vehicles. Moreover, with the rescission of the BMW interpretation and the issuance of this interpretation, we now conclude that vehicles manufactured in the United States that are certified by controlling companies may have VINs that incorporate the controlling company’s WMI, regardless of whether the controlling company has a U.S.-issued WMI. 

NHTSA would like to note, however, that there are still restrictions on who can be identified as the manufacturer in the WMI. As explained above, the WMI must identify the certifying manufacturer. Additionally, out of concern for the dwindling supply of WMIs, NHTSA will direct its contractor not to issue new U.S. WMIs specifically for vehicles produced outside of the United States, even when the manufacturer is a U.S-headquartered company.19 That is, manufacturers that are headquartered in the United States may use existing WMIs on vehicles they produce in other countries, but they will not be able to obtain new WMIs for that purpose.20 Because Ford is headquartered in the U.S. and has been issued U.S. WMIs, NHTSA regulation would not prohibit Ford from using its U.S.-issued WMIs on vehicles it manufactures in Country X for sale in the United States. 

I hope this information is helpful. If you have any further questions, please feel free to contact Callie Roach of my staff at this address or at (202) 366-2992.
 

Sincerely,
ADAM RAVIV
Adam Raviv Chief Counsel

Dated: 9/11/24
Ref: Part 565

19 This decision to deviate from ISO 3780, which specifies that WMIs are issued by the WMI-issuing authority in the country in which it is headquartered, ensures that U.S. WMIs are not issued to entities lacking a substantial presence in the United States.
20 When requesting a new U.S. WMI for a particular vehicle type, manufacturers will need to provide information substantiating that they will be producing that vehicle type in the United States.

ID: NJP Engineering Letter of Interpretation FMVSS No. 121signed

October 4, 2024

Mr. Nick Paulick, PE
Owner, NJP Engineering, LLC
P.O. Box 2161
Oshkosh, WI 54903 

Dear Mr. Paulick, 

This responds to your letter, dated October 31, 2022, regarding removing the third axle from a used three axle semitrailer and reducing both the trailer’s load-carrying capacity and its braking capacity. More specifically, we understand you to be asking whether the reduction in braking capacity would violate the “make inoperative” prohibition in 49 U.S.C. § 30122 with respect to Federal motor vehicle safety standard (FMVSS) No. 121, Air Brake Systems. 

Please note that our answer below is based on our understanding of the specific information provided in your letter. This interpretation letter does not have the force and effect of law and is not meant to bind the public in any way. This letter is intended only to provide clarity regarding existing requirements under the law and represents the opinion of the agency on the questions addressed in your letter at the time of signature. 

In your letter, you stated that you are requesting an interpretation regarding the modification of semi-trailers after first sale to add or remove axles to change their load-carrying capacity and the overall capacity of a combination motor vehicle. You note that you reviewed existing interpretations (specifically, our letter to John Paul Barber on May 24, 1993) and believe that the National Highway Traffic Safety Administration (NHTSA) “is not opposed” to aftermarket modifications such as removing an axle, “so long as they are done properly and that an explanatory label is affixed, advising the user of what these changes will mean in terms of gross weight rating.” 

You ask about the specific example of a three-axle semi-trailer with each axle having a gross axle weight rating (GAWR) of 20,000 pounds and the trailer having a gross vehicle weight rating (GVWR) of 75,000 pounds. You suggest the removal of one axle from the trailer, reducing its GVWR to 65,000 pounds. You further state that a “dataplate” would be permanently affixed to the modified trailer advising the user of the revised payload capacity. Because removing an axle from the trailer also removes the brakes associated with it, you ask whether the reduced “braking capacity” of the trailer would bring the vehicle out of compliance with NHTSA’s braking standards and potentially violate the “make inoperative” prohibition. For the purposes of this letter of interpretation, we understand “braking capacity” as used in your letter to mean the ability of the vehicle to meet the stopping distance requirements in FMVSS No. 121. 

By way of background, NHTSA is authorized by the National Traffic and Motor Vehicle Safety Act (Safety Act, 49 U.S.C. Chapter 301) to issue FMVSS that set performance requirements for new motor vehicles and new items of motor vehicle equipment. The Safety Act requires manufacturers to self-certify that their vehicles and equipment conform to all applicable FMVSS in effect on the date of manufacture. NHTSA also investigates safety-related defects. 

Your letter indicates that the modifications occur after first sale other than for resale.1 As you correctly note, the only legal requirement that is imposed on entities that make modifications to used vehicles is that a manufacturer, distributor, dealer, rental company, or motor vehicle repair business may not knowingly make inoperative any part of a device or element of design installed in furtherance of compliance with an applicable motor vehicle safety standard. 49 U.S.C. § 30122(b). A modifier subject to this prohibition must therefore ensure that the vehicle’s brakes and other systems remain in compliance with all applicable Federal motor vehicle safety standards once the modifications are performed. Civil penalties can be imposed under 49 U.S.C.
§ 30165(a) for violations of section 30112(b). 

We assume, for the purposes of this letter, that the trailer you intend to modify is equipped with an air brake system. FMVSS No. 121 establishes requirements for vehicles equipped with air brake systems. Under S5.3.1 of FMVSS No. 121, truck tractors must meet the stopping distance requirements specified in Table II of that standard, when loaded to their GVWR and tested using an unbraked control trailer.2 We note, however, that such requirements are applicable to the truck tractor. FMVSS No. 121 contains no stopping distance requirements applicable to trailers. FMVSS No. 121 does contain other requirements applicable to trailers, such as parking brakes, and certain as-equipped requirements should the trailer axles have brakes, such as that the braked trailer axles be equipped with anti-lock braking systems and have the required air reservoirs. 

We also assume for the purposes of this letter that the entity performing the modifications is subject to the “make inoperative” prohibition. You state that NJP Engineering provides engineering services for the evaluation of new and modified cargo tank motor vehicles. From this description, it is not clear what role NJP Engineering has in the actual performance of any modifications. We also note that even if an entity not subject to the “make inoperative” prohibition modifies the vehicles, such modifications may be subject to the laws and regulations administered by the Federal Motor Carrier Safety Administration and the States in which the vehicles are operated.

1 Because the trailer is a used trailer, you are not an alterer. An alterer is defined as a person who alters by addition, substitution, or removal of components (other than readily attachable components) a certified vehicle before the first purchase of the vehicle other than for resale. 49 C.F.R. § 567.3.
2 The following vehicles may meet the stopping distance requirements specified in Table IIa instead of Table II: Three-axle tractors with a front axle that has a GAWR of 14,600 pounds or less, and with two rear drive axles that have a combined GAWR of 45,000 pounds or less, that were manufactured before August 1, 2011; and all other tractors that were manufactured before August 1, 2013. For such vehicles, the analysis in this letter of interpretation is the same. 

In your letter, you state that a three-axle trailer would be modified to remove an axle and you ask about the applicability of the “make inoperative” prohibition with respect to the trailer’s braking capacity. FMVSS No. 121 does not contain stopping distance requirements applicable to trailers. Therefore, a reduction in braking capacity alone would not affect compliance with the FMVSSs and would not violate the “make inoperative” prohibition.3 Regarding other braking performance requirements applicable to trailers, such as parking brake requirements and as- equipped requirements for trailer axles, modifications to the trailer as stated must not take the trailer out of compliance with requirements that would be applicable to the modified trailer. You do not ask about, nor does this letter address, any other aspect of compliance with FMVSS No. 121, or other applicable FMVSS. 

I hope this information is helpful. If you have any further questions, please feel free to contact Eli Wachtel of my staff at (202) 366-2992.

Sincerely,
ADAM RAVIV
Adam Raviv Chief Counsel

Dated: 10/4/24
Ref: Standard No. 121

3 You note that you intend to affix a “dataplate” indicating the revised weight capacity of the trailer. We note that such a “dataplate” is not required by our regulations; however, we believe it is appropriate to add a label to the vehicle which indicates the appropriate loaded weight of the modified vehicle in situations where certain modifications that might be made to a used vehicle (e.g., adding or deleting an axle) which could make the originally assigned GVWR inappropriate for the vehicle as modified.
 

ID: Maxzone Interpretation EPLLA 571.108_(002) signed

October 4, 2024

VIA EMAIL

Ms. Penny Chiu 

Product Marketing Coordinator 

Maxzone Auto Parts Corp. 

mkt1363@maxzone.com

Dear Ms. Chiu, 

This responds to your email, dated July 7, 2023, seeking a legal interpretation regarding the proper calculation of the “effective projected luminous lens area” (EPLLA) under Federal Motor Safety Standard (FMVSS) No. 108, Lamps, reflective devices, and associated equipment, and the inclusion of a “diffusion element,” as well as the “distinctive water wave pattern” on your product. You also submitted additional information via email to NHTSA staff, such as diagrams of your product and other supporting information, on June 28, 2023, and July 12, 2023, which was taken into consideration in developing this response. 

In responding to this request, NHTSA notes that the contents of this letter do not have the force and effect of law and are not meant to bind the public in any way. This letter is only intended to provide clarity regarding existing requirements under the law at the time of signature. 

Based on the information you have provided and for the reasons explained below, our answer is that the area you describe as the “diffusion element” and the area you describe as having a “distinctive water wave pattern” can be included in the calculation of the EPLLA of your lamp under FMVSS No. 108 only if those elements are not transparent and direct light toward the photometric test pattern. However, based on the information you have provided, we are unable to state whether such elements do or do not perform such a function. 

Background 

NHTSA is authorized by the National Traffic and Motor Vehicle Safety Act (Safety Act, 49 U.S.C. Chapter 301) to issue FMVSS that set performance requirements for new motor vehicles and new items of motor vehicle equipment. NHTSA does not provide approvals of motor vehicles or motor vehicle equipment. Instead, manufacturers are required to self-certify that their products conform to all applicable FMVSSs that are in effect on the date of manufacture before the products can be offered for sale. In so doing, manufacturers must have some independent basis for their certification that a product complies with all applicable safety standards, and they must ensure that the vehicle would comply when tested by NHTSA.1 This requirement does not necessarily mean that a manufacturer must conduct the specific tests set forth in an applicable standard, in this case FMVSS No. 108. Certifications may be based on, among other things, engineering analyses, actual testing, and computer simulations. Whatever the basis for certification, however, the manufacturer must certify that the product complies with a standard as it is written, i.e., that the vehicle will pass all applicable requirements if it is tested exactly according to the standard’s test conditions and other specifications. Manufacturers must also ensure their products are free of safety-related defects. This letter represents NHTSA’s opinion concerning how your product, as you describe it, would be analyzed under FMVSS No. 108. It is not an approval of your product. 

In your July 7, 2023, email, you ask whether the EPLLA of your lamp, as defined in FMVSS No. 108, should include the area you describe as the “diffusion element,” or only the area you describe as the “refractive element.”2 You note that what you describe as the “diffusion element” of your product includes scattering structures as well as a “distinctive water wave pattern,” which you state “serves the purpose of diffusing light” and which you believe contributes to spreading the light emitted from the lamp. Your June 28 email includes two diagrams of the product which you state show the product’s EPLLA3 and the impact of the scattering structures on the surface. Finally, your July 12 email includes an image identifying the elements of your lamp. We note that although your question is regarding your product, which is a turn signal lamp, you have not asked about the EPLLA requirements applicable to a specific type of motor vehicle lamp. Therefore, your question, and this response, may be applicable to multiple lamp types. 

FMVSS No. 108, S6.4.1 states that “[e]ach turn signal lamp, stop lamp, high-mounted stop lamp, and school bus signal lamp must meet the applicable effective projected luminous lens area requirement specified in Tables IV–a, IV–b, and IV–c.” Furthermore, the lens area certification and compliance option in S6.4.3(a) states that “[w]hen a vehicle is equipped with any lamp listed in Table V–b each such lamp must provide not less than 1250 sq mm of unobstructed effective projected luminous lens area in any direction throughout the pattern defined by the corner points specified in Table V–b for each such lamp.” Table V-b includes turn signal lamps, stop lamps, taillamps, and parking lamps. Turn signal lamps certified under the lens area option must provide unobstructed minimum effective projected luminous lens area of 1250 sq mm at a horizontal angle of 45° and a vertical angle of 15°. 

As defined in FMVSS No. 108, EPLLA “means the area of the orthogonal projection of the effective light-emitting surface of a lamp on a plane perpendicular to a defined direction relative to the axis of reference. Unless otherwise specified, the direction is coincident with the axis of reference.”

1 Letter to Helen A. Rychlewski, responding to letter received June 7, 1995, available at https://www.nhtsa.gov/interpretations/aiam5591.
2 Your submission also cites to the definition of “Diffusion Element” in Society of Automotive Engineers standard J2999. This definition is not incorporated into FMVSS No. 108.
3 The image submitted appears to indicate that your calculated EPLLA is 5648.159 sq mm.

FMVSS No. 108 also defines “effective light-emitting surface” as “that portion of a lamp that directs light to the photometric test pattern, and does not include transparent lenses, mounting hole bosses, reflex reflector area, beads or rims that may glow or produce small areas of increased intensity as a result of uncontrolled light from an area of ½° radius around a test point.” 

The definition of “effective light-emitting surface” was added to FMVSS No. 108 in a final rule published on August 11, 2004 (2004 final rule).4 This action amended the standard for turn signal lamps, stop lamps, taillamps, and parking lamps to increase compatibility with the requirements of the Economic Commission for Europe and to improve the visibility of these lamps. In the 2004 final rule, NHTSA responded to comments on the proposed amendments and definitions. In so doing, we noted that “transparent lenses cannot be included in the determination of the effective light-emitting surface.”5 Furthermore, we also stated the following:

“[T]here does not appear to be any substantive change in determining the effective projected luminous lens area. However, the proposed definition clearly stated that only the portion of the lamp that directs light to the photometric test pattern may be included in the determination of the effective light-emitting surface. … we believe that transparent lenses do not direct light to the photometric test pattern and may not be included in the calculation. However, portions of translucent lenses intended to deliberately scatter the beam pattern within the allowable photometry (e.g., frosted or stippled lenses), are permissible as part of the effective projected luminous lens area.”6 

This statement makes clear that EPLLA does include translucent structures that direct light to the photometric test pattern by diffusing or scattering light, even if such structures are on otherwise transparent lenses. 

Discussion 

We now turn to your questions regarding your product. We understand you to be asking two distinct but related questions. First, whether the area that you describe as the “diffusion element” may be included for EPLLA? Second, does the presence of what you describe as the “distinctive water wave pattern” allow an area to be included in the EPLLA? We take these questions in turn. 

Regarding the first question, the definition of effective light-emitting surface makes clear that the area of transparent lenses may not typically be included in the calculation of the effective light

4 69 FR 48805 (Aug. 11, 2004). See also Letter to Dennis Moore, Nov. 15, 2006, at https://www.nhtsa.gov/interpretations/06-003601as.
5 69 FR 48805, 48811 (Aug. 11, 2004). This statement was consistent with a June 14, 2000, letter of interpretation in which we stated that the transparent lens covering a large lamp assembly was not the “outer lens surface” of a turn signal lamp that is part of that assembly for the purposes of calculating its visibility requirements. Letter to Shigeyoshi Aihara, June 14, 2000, at https://www.nhtsa.gov/interpretations/20836ztv.
6 69 FR 48805, 48811 (Aug. 11, 2004).

emitting surface. As explained in the 2004 final rule, such elements do not direct light toward the photometric test pattern. 

However, as we have stated in the past, areas of otherwise transparent lenses that incorporate scattering structures, such as frosted or stippled lenses, as well as certain cuts such as prism or pillow cuts and other similar structures, are not “transparent” for purposes of determining the effective light-emitting surface. Rather, these areas are “translucent” and may be included in the calculation of EPLLA, so long as such elements direct the light to the photometric test pattern. Based on the submitted materials, it appears that the area of the “diffusion element” you describe on the lens on your product has such cuts. If these cuts direct light toward the photometric test pattern, then the area of these cuts may be counted as part of your product’s EPLLA. 

We now turn to your second question regarding the “distinctive water wave pattern.” Similarly, if the “distinctive water wave pattern” has the effect of scattering light and directing the light toward the photometric test pattern, then its area may be included in the calculation of the effective light-emitting surface (and therefore, EPLLA). We note, however, that we are unable to determine whether the wave pattern has such an effect based on the information you have provided. As previously stated, the manufacturer must certify the product as compliant with the applicable standards and must exercise reasonable care in making such a certification. 

I hope this information has been helpful. If you have further questions, please contact Eli Wachtel of my staff at (202) 366-2992. 

Sincerely,
ADAM RAVIV
Adam Raviv Chief Counsel

Dated: 10/4/24
Ref: Standard No. 108

ID: NCC-230308-001 NelsonMullinsParkingBrakeIndicatorInterp

October 31, 2024

Ms. Christie L. Iannetta
Nelson Mullins Riley & Scarborough LLP
101 Constitution Ave, NW, Suite 900
Washington, DC 20001

Dear Ms. Iannetta:

This interpretation responds to your letter regarding Federal Motor Vehicle Safety Standard (FMVSS) No. 135, Light vehicle brake systems. Specifically, you asked about paragraph S5.5.1 of FMVSS No. 135, which outlines the requirements for when certain brake indicators must be activated. Your question focuses on subparagraph (c), which requires that an indicator be activated when there is “[a]pplication of the parking brake.” You asked the agency to confirm that “a parking brake visual indicator that illuminates when a driver intentionally activates the electronic parking brake via the park brake control meets the requirements of FMVSS No. 135, S5.5.1(c), but that when the same electronic parking brake is automatically applied by the vehicle, the parking brake visual indicator may, but is not required, to illuminate to be considered compliant with this same provision.” Based on the information you have provided, our answer is that this requested confirmation does not provide an accurate understanding of FMVSS No. 135. To comply with FMVSS No. 135, a parking brake indicator must be activated whenever a parking brake is engaged, regardless of how the parking brake is applied.

Background
By way of background information, the National Highway Traffic Safety Administration (NHTSA) does not provide approvals of motor vehicles or motor vehicle equipment. Under 49 U.S.C. Chapter 301, manufacturers are required to ensure that their vehicles and equipment meet applicable requirements.

Please also note that our answer below is based on our understanding of the specific information provided in your letter. This interpretation letter does not have the force and effect of law and is not meant to bind the public in any way. This letter is intended only to provide clarity regarding existing requirements under the law and represents the opinion of the agency on the questions addressed in your letter at the time of signature.

FMVSS No. 135
FMVSS No. 135 establishes requirements for light vehicle braking systems. Paragraph S5.5.1 of FMVSS No. 135 requires indicators to be activated when the ignition (start) switch is in the “on” (“run”) position and one or more of seven scenarios occur. Paragraph (c) of S5.5.1 requires an indicator to be activated upon “application of the parking brake.” So if the parking brake is applied and the vehicle’s ignition is in the “on” position, a parking brake indicator must be activated.

Your Question and NHTSA’s Response
In your letter, you describe a manufacturer’s Electronic Parking Brake (EPB) system. You indicate the EPB system is integrated into the rear foundation brake calipers and is not separately serviceable. Your letter states that the EPB can be applied manually by the driver or automatically by the system. When the driver manually applies the parking brake control, upon successful confirmation of engagement of the EPB, a visual indicator appears on the user interface in plain view of the driver. You state that the EPB visual indicator remains illuminated while the EPB is engaged as a reminder to the driver to manually release the parking brake before driving.

In addition to the manual application of the parking brake, your letter indicates that there are scenarios when the EPB automatically engages, even when the driver does not manually activate the EPB, including when the vehicle is shifted into park. You explain that if a driver puts the vehicle in park and does not manually apply the parking brake, the vehicle will automatically apply the EPB. If the vehicle automatically applies the EPB, the parking brake indicator is not activated. Lastly, you indicate that when the driver shifts out of park, the EPB system is automatically deactivated.

In your letter, you assert the manufacturer’s view that this system is compliant with FMVSS No. 135 S5.5.1(c) because the regulation requires display of the parking brake only when the driver manually applies the parking brake. You point to previous interpretations that NHTSA has published, where we explain that the parking brake indicator requirement was promulgated to ensure drivers do not drive with the parking brake engaged. You assert that because the manufacturer’s EPB system eliminates this risk, the system should be considered compliant. Additionally, you assert that the regulatory history and language of the standard point to this system being compliant under paragraph S5.5.1.

After careful consideration of both the standard and the arguments made in your letter, the agency has concluded that the EPB system described in your letter would be considered noncompliant with FMVSS No. 135 S5.5.1(c). As discussed above, FMVSS No. 135 S5.5.1(c) requires that if a vehicle ignition is switched to the “on” position and the parking brake is applied, an indicator must activate to inform the driver of the status of the parking brake. From the details in your letter, there would be scenarios where the vehicle you described would have the ignition switched to the “on” position with the parking brake applied, but the parking brake indicator would not be activated. To use the example from your letter, if a driver puts the vehicle in the park position and does not activate the parking brake manually, the parking brake will automatically apply, but no parking brake indicator will be active. The system you describe in
your letter would be considered noncompliant under FMVSS No. 135 S5.5.1(c). Simply put, if the parking brake is applied, the parking brake indicator must be activated.

Your letter asserts that the phrase “application of the parking brake” in paragraph S5.5.1(c) refers to an action that the driver takes via the “parking brake control.” You state that a driver cannot “apply” a parking brake system, but only the control, meaning that the parking brake indicator requirement only applies when the driver manually applies the parking brake. We disagree with this reading, which is inconsistent with both the language and the intent of the standard. Had S5.5.1(c) been intended to cover only manual application of the parking brake control, it would say so. Other parts of FMVSS No. 135 refer to application and activation of the “parking brake control”1; by contrast, S5.5.1(c) refers more generally to the “parking brake.” Moreover, FMVSS No. 135 makes multiple references to manual application, actions, or controls, without doing so in S5.5.1(c).2

As you state in your letter, when FMVSS No. 135 was first promulgated, manual application of the parking brake was the only way a parking brake could be engaged. However, FMVSS No. 135 has been updated multiple times since it was first issued in 1995, including as recently as 2022,3 and it has never been amended to specify that S5.5.1(c) applies only to manual application of the “parking brake control.” This history, and the lack of a manual application requirement or reference to the parking brake control in S5.5.1(c), show the agency intended the parking brake indicator to be active whenever the parking brake is engaged, regardless of how the brake is engaged.

Moreover, if S5.5.1(c) covered only manual application of the parking brake control, then no indicator would be required when a vehicle automatically engages the parking brake, even if nothing prevents the vehicle from driving during this engagement—a circumstance when an indicator would be especially essential because the driver may not have consciously activated the parking brake. In fact, your letter’s description of the manufacturer’s EPB system suggests there may be circumstances where the parking brake in the manufacturer’s vehicle is automatically engaged other than when the driver shifts the vehicle to “Park.”

The distinction your letter makes between a vehicle’s “parking brake” and its “parking brake system” does not change this analysis. “Parking brake system” has no regulatory definition.4 “Parking brake,” which is the term used in S5.5.1(c), is defined as “a mechanism designed to prevent the movement of a stationary motor vehicle.”5 The definition does not distinguish between mechanisms that are activated by a designated manual control and mechanisms that are activated by other means. S5.5.1(c) simply requires activation of the indicator when the parking brake mechanism is engaged.

The agency has also considered the arguments you made in your letter regarding previous interpretations NHTSA has published on the parking brake indicator requirement. NHTSA has indicated in interpretations that the purpose of the parking brake indicator requirement is to prevent drivers from driving their vehicles with the parking brake activated. Doing so could potentially lead to excessive wear on the transmission and parking brake system, which could cause a variety of safety issues.6 However, just because a manufacturer has designed a system that purports to resolve, though other means, a safety concern addressed in an FMVSS does not mean that it is not bound by the requirements of the FMVSS or that it may introduce noncompliant motor vehicles or motor vehicle equipment to the market. If a manufacturer believes that it has developed technology that makes certain regulatory requirements unnecessary, it may petition the agency for a rulemaking to amend the relevant requirements. It may also request an exemption from an applicable standard if it has reason to believe it is eligible.7 Otherwise, the current requirements apply.

Accordingly, the plain meaning and intent of S5.5.1(c) is for the parking brake indicator to be active any time the parking brake is engaged and the vehicle’s ignition is in the “on” position. This requirement applies regardless of whether the parking brake is engaged through the manual application of the designated parking brake control or through other means.

I hope this letter answers all of your questions. If you have any further questions regarding this matter, please feel free to contact Mr. Matthew Filpi of my staff at (202) 366-2992.

Sincerely,
ADAM RAVIV
Adam Raviv Chief Counsel
 

Dated: 10/31/24
Ref: Standard No. 135

1 See FMVSS 135 S.7.12.2(b), (i), (l).
2 See FMVSS 135 S5.3.2, S6.3.5, S6.3.11.2.
3 See 87 FR 34810 (Jun. 8, 2022).
4 The only published definition your letter provides for “parking brake system” is a proposed definition, never implemented, in FMVSS No. 121, which is a separate standard for air brake systems in trucks, buses, and trailers. Your letter also argues that “[t]he driver cannot ‘apply’ the parking brake system, only the control (e.g., using a lever or button).” In fact, FMVSS No. 135 indicates otherwise: it discusses how to test the parking brake “[i]n the case of a parking brake system that does not allow application of the specified force in a single application.” S7.12.2(j).
5 49 C.F.R. § 3(b).
6 See Letter to Headley, May 30, 2002, available at https://www.nhtsa.gov/interpretations/23871jeg#:~:text=We%20noted%20that%20the%20purpose%20of%20the,wa s%20applied%20(and%20hence%20should%20be%20released; see also Letter to Selander, Apr. 29, 2002, available at https://www.nhtsa.gov/interpretations/6992.
7 See, e.g., 49 C.F.R. § 556.

ID: NCC-230120-001 571.108 Peterson Trailer Auxiliary Door Light 11.06.24 signed

November 6, 2024

Mr. Donald Lane 

Peterson Manufacturing Co. 

4200 E. 135th Street Grandview, MO 64030 

dlane@pmlights.com

Dear Mr. Lane: 

This responds to your letter, received January 6, 2023, in which you requested a letter of interpretation asking whether a lamp located on the front of a trailer that would illuminate green or red to indicate whether the trailer doors are open or closed is compliant with Federal Motor Vehicle Safety Standard (FMVSS) No. 108, Lamps, reflective devices, and associated equipment. Based on the information you provided in your letter, as explained in more detail below, we have concluded that installing the lights as described would not be permissible under FMVSS No. 108. 

In responding to this request, NHTSA notes that the contents of this letter do not have the force and effect of law and are not meant to bind the public in any way. This letter is only intended to provide clarity regarding existing requirements under the law at the time of signature. 

Background 

NHTSA is authorized by the National Traffic and Motor Vehicle Safety Act (Safety Act, 49 U.S.C. Chapter 301) to issue FMVSS that set performance requirements for new motor vehicles and new items of motor vehicle equipment. The Safety Act requires manufacturers to self-certify that their vehicles and equipment conform to all applicable FMVSS in effect on the date of manufacture. NHTSA also investigates safety-related defects. After first purchase of a vehicle or equipment in good faith other than for resale, section 30122 of the Safety Act requires that a manufacturer, distributor, dealer, rental company, or motor vehicle repair business not knowingly make inoperative any part of a device or element of design installed on or in a motor vehicle or motor vehicle equipment in compliance with an applicable motor vehicle safety standard. This letter represents NHTSA’s opinion concerning whether your design, as you describe it, would be permitted under FMVSS No. 108 and section 30122. 

In your letter, you state that you have been asked to install an “auxiliary light” on trailers at or over 2032mm in width and 8.1m in length. The light would be installed on the front of the trailer “so as to be visible to the driver in the driver’s side mirror” and would illuminate green when the trailer doors are shut and red when at least one of the trailer doors are open. Although it is not clear from your description, we assume that the light would also be visible to other individuals looking at the trailer from the front. You also state that you intend for the lamp to only illuminate on the private property of the trailer owner, not on other roads. You ask whether the light could be made with green and red LEDs and clear lenses or in the alternative use green or red lenses. 

Requirements of the Standard 

FMVSS No. 108 specifies requirements for original and replacement lamps, reflective devices, and associated equipment, including for trailers. For auxiliary lamps, the primary restriction imposed by FMVSS No. 108 is by S6.2.1, which states that “[n]o additional lamp, reflective device, or other motor vehicle equipment is permitted to be installed that impairs the effectiveness of lighting equipment required by this standard.” Both original equipment and aftermarket lighting can run afoul of the “make inoperative” provision, and NHTSA considers the installation of an aftermarket lamp to violate the “make inoperative” provision if the installation of the same lamp as original equipment would violate FMVSS No. 108.1 Therefore, while you do not state in your letter whether your installation would be as original equipment or in the aftermarket, we conduct the same impairment analysis. These prohibitions bar installation by a manufacturer, distributor, dealer, rental company, or motor vehicle repair business of lamps that would impair the effectiveness of required lighting, but do not apply to the owner of a vehicle. 

Typically, the impairment determination under FMVSS No. 108 S6.2.1 is made on a case-by- case basis and considers four main characteristics of the auxiliary lamp to analyze whether it impairs the effectiveness of required lighting: the brightness, color, location, and activation pattern of the lamp. This list is not exhaustive and other considerations may be relevant to the analysis. NHTSA has long maintained that highway traffic safety is enhanced by drivers’ familiarity with established lighting schemes, which facilitates their ability to instantly recognize the meaning the lamps convey and respond accordingly. Therefore, NHTSA has interpreted the impairment provision to prohibit auxiliary lamps that are colors and are mounted in locations which are likely to cause confusion to other road users. For auxiliary lamps located on the front of vehicles, these colors include red, which could be confused for a taillamp or stop lamp, and green, which typically conveys the message that one may proceed forward and could therefore impair required lighting that indicates caution.2 

1 See, e.g., Letter to Timothy C. Murphy (Nov. 1, 2004), available at
https://www.nhtsa.gov/interpretations/gf006332.
2 See Letter to Paul Schaye (Sept. 9, 2019), available at https://www.nhtsa.gov/interpretations/571108-ama-schaye- front-color-changing-light; See also, Letter to Kerry Legg (Oct. 19), 2006, available at https://www.nhtsa.gov/interpretations/legg1. 

For required lighting relevant to your inquiry, FMVSS No. 108 requires that all trailers have two red taillamps and two red stop lamps on the rear of the trailer, at the same height, symmetrically about the vertical centerline, and as far apart as practicable. Also, all trailers of 2032 mm or more in width must have three red identification lamps on the rear, at the same height as one another, as close to the top of the trailer as practicable and as close as practicable to the vertical centerline of the trailer, with lamp centers spaced not less than 6 inches or more than 12 inches apart. Additionally, such trailers must also have two amber clearance lamps on the front and two red clearance lamps on the rear, symmetrically mounted about the vertical centerline as near the top as practicable to indicate the overall width of the trailer.3 

Discussion 

We now turn to your inquiry. As an initial matter, it is immaterial to this analysis that the lamp is intended to illuminate only on the trailer owners’ property. NHTSA’s longstanding position is that when the vehicle is designed to be used on-road, its equipment must meet all applicable FMVSS.4 

Your lamp is not required equipment and so would be considered, as you correctly describe it, as auxiliary or supplemental lighting. Therefore, we turn to the question of impairment and look to the relevant characteristics.5 The factors most relevant to your inquiry are the location and color of the lamps, which we analyze together. We find that the lamp design described in your letter is likely to impair the effectiveness of the identification and clearance lamps required by FMVSS No. 108, and, if installed by you or another entity subject to the “make inoperative” prohibition as aftermarket equipment, would impair the effectiveness of that required lighting installed in compliance with FMVSS No. 108. 

By requiring different colored lamps on the front and the rear of trailers, FMVSS No. 108 facilitates rapid recognition by road users of the direction that a trailer is facing or is moving. Because your device illuminates red in the front of the trailer, it operates contrary to this standard’s intention. This lighting arrangement could cause drivers to mistake the front of the trailer for the rear. Such a mistake, even if only for a moment, may cause drivers to take unnecessary, and possibly unsafe, driving maneuvers or to fail to take other maneuvers in time to

3 FMVSS No. 108 Table I-a.
4 See Letter to Paul Crunk (Aug. 11, 2000), available at https://www.nhtsa.gov/interpretations/21872ztv.
5 Regarding activation pattern, NHTSA interprets FMVSS No. 108 to require that all auxiliary lamps be “steady burning,” with the sole exception being auxiliary lamps that supplement required lamps that flash, such as turn signals. For the purposes of this letter, we assume the lamps you describe would be steady burning when activated.
Before 2007, FMVSS No. 108 included an explicit requirement that, with the exception of certain types of required lamps (e.g., turn signal lamps), all lamps on a vehicle, including auxiliary lamps, must be steady burning. In 2007, NHTSA implemented an administrative reorganization of FMVSS No. 108 which, among other things, converted the blanket “steady burning” requirement (and its exceptions) into individual activation requirements for each type of required lamp. See 72 FR 68234 (Dec. 4, 2007). Although the reorganized rule no longer includes a blanket “steady burning” requirement, NHTSA stated in the preamble to the reorganized rule that its “rewrite of FMVSS No. 108 is considered administrative in nature because the standard’s existing requirements and obligations are not being increased, decreased, or substantively modified.” Moreover, NHTSA continues to believe that flashing auxiliary lamps would impair the effectiveness of required lamps by distracting or confusing other road users.

prevent dangerous events. Therefore, it would impair the effectiveness of the identification and clearance lamps required on trailers. Additionally, when the device is activated green, it may give the misimpression to road users that it is safe to proceed forward when in fact it may not be safe to do so, which would impair the effectiveness of various required lamps intended to communicate caution, such as stop lamps. Our opinion is the same regardless of whether the light uses green or red colored light sources or colored lenses. 

We hope you find this information helpful. If you have further questions, please contact Eli Wachtel of my staff at (202) 366-2992. 

Sincerely,
Adam Raviv
Chief Counsel

Dated: 11/6/24
Ref: Standard No. 108

ID: NCC-231206-001 - Steptoe VanHool FMVSS 217 Emergency Exit Requirements 11-25-2024 signed

November 25, 2024 

David H. Coburn Steptoe LLP 

1330 Connecticut Avenue, NW 

Washington, DC 20036-1795 

Dear Mr. Coburn: 

This responds to your letter dated December 5, 2023, on behalf of Belgium-based bus manufacturer Van Hool NV regarding the emergency exit identification requirements under 49 C.F.R. § 571.217 S5.5.1 for buses other than school buses. You asked whether the requirements under S5.5.1 to designate emergency exits and provide concise operating instructions for these exits may be satisfied by pictograms, without the use of text. This letter responds to that request. 

In responding, the National Highway Traffic Safety Administration (NHTSA) notes that the contents of this letter do not have the force and effect of law and are not meant to bind the public in any way. This letter is only intended to provide clarity regarding existing requirements under the law at the time of signature. 

Section 5.5.1 requires in pertinent part: 

For buses other than school buses…each emergency exit door shall have the designation “Emergency Door” or “Emergency Exit,” and every other emergency exit shall have the designation “Emergency Exit” followed by concise operating instructions describing each motion necessary to unlatch and open the exit, located within 16cm of the release mechanism. 

S5.5.1 provides explicit designation requirements. The use of quotations in the standard indicates that the exact words “Emergency Door” or “Emergency Exit” are necessary for compliance and that a pictogram by itself will not suffice. Thus, a pictogram may not be provided in lieu of text. This position aligns with NHTSA’s earlier interpretation in Letter to Vincent P. Schulze (June 22, 1998).1 

With regard to the “concise operating instructions” required by the standard, S5.5.1 does not set forth explicit language that must be used, nor does it otherwise expressly prohibit the use of pictograms, symbols, icons or similar. The standard requires only that the instructions “describ[e] each motion necessary to unlatch and open the exit.” It further provides examples of operating instructions as follows: “(1) Lift to Unlatch, Push to Open; and (2) Lift Handle and Push out to Open.”

1 Available at www.nhtsa.gov/interpretations/17175drn (declining the use of a symbol in lieu of words for emergency egress windows). 

While the text examples provided in the standard are not exhaustive given the breadth of variation in vehicle emergency exit design, NHTSA emphasizes the need to ensure that passengers can quickly access both the emergency exit and the instructions for the exit’s release mechanism. The agency has noted that “[i]n an emergency, persons are used to finding an emergency exit where they see a label with the designation ‘Emergency Exit.’”2 Moreover, the standard “nowhere draws any distinction between markings designating an exit as an emergency exit and markings setting forth operating instructions for the emergency exit.”3 This interpretation suggests that both the emergency exit designation and the operating instructions were intended to be text-based. 

Diluting the emergency egress marking requirements would be consequential to motor vehicle safety.4 At present, the agency has no data to support that a particular set of pictograms5 will be easily and universally understood by bus passengers in the United States. That U.N. Regulation No. 1076 allows for safety sign pictograms and has been accepted in the European Union7 does not inform or guarantee that an American audience will understand and accept the same pictograms. 

As you acknowledged, NHTSA intends its policies to both promote international harmonization and avoid unnecessary design restrictions. If a manufacturer wishes to produce vehicles with pictorial emergency egress markings not currently permitted under Standard 217, it may elect to file a petition for rulemaking on the issue. 

I hope this information is helpful. If you have any further questions, please feel free to contact Evita St. Andre of my staff at this address or (617) 494-2767. 

Sincerely,
ADAM RAVIV
Adam Raviv Chief Counsel

Dated: 11/25/24
Ref: Standard No. 217 

2 Letter to John G. Sims (Jan. 26, 1990), available at www.nhtsa.gov/interpretations/nht90-124.
3 Id.
4 See Denial of a Petition for Forest River Inc., 86 FR 56351 (Oct. 8, 2021) (misplacement of the emergency egress labels by 9cm).
5 Van Hool submitted that NHTSA may require that pictograms used to comply with S5.5.1 adhere to either the International Organization for Standardization (ISO) standard 3864-1:2011, paragraph 6.5, or the American National Standards Institute (ANSI) standard Z535.
6 U.N. Regulation 107, “Concerning the Adoption of Harmonized Technical United Nations Regulations for Wheeled Vehicles, Equipment and Parts which can be Fitted and/or be Used on Wheeled Vehicles and the Conditions for Reciprocal Recognition of Approvals Granted on the Basis of these United Nations,” Revision 8 (Feb. 14, 2023), available at unece.org/sites/default/files/2023-02/R107r8e.pdf
7 Framework Regulation (EU) 2018/858 of the European Parliament and of the Council (May 30, 2018), available at
https://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX:02018R0858-20230730&qid=1699805899877

ID: NCC-241023-001TSEI-TIMA Letter of Interpretation 571.108 Flashing Amber Lights 12-13-2024.signed.

December 13, 2024

Mr. Chuck Polley

Transportation Safety Equipment Institute

c/o Grote Industries LLC

2600 Lanier Drive

Madison, IN 47250

Mr. John Freiler

Truck Trailer Manufacturers Association

7001 Heritage Village Plaza

Suite 220

Gainesville, VA 20155-3094

Dear Messrs. Polley and Freiler:

This responds to your letter requesting clarification of Federal Motor Vehicle Safety Standard (FMVSS) No. 108, Lamps, reflective devices, and associated equipment, regarding flashing “emergency warning lights.” I apologize for the delay in responding. As used in your letter, the term “emergency warning lights” generically refers to a category of vehicle lighting equipment that consists of one or more amber-colored flashing or strobing lamps that is typically installed on certain types of slow-moving vehicles and utility vehicles (such as tow trucks, repair vehicles, or vehicles transporting oversized loads) to call the attention of other drivers to the presence of these vehicles. 

You ask that the National Highway Traffic Safety Administration (NHTSA) provide clarification of its longstanding interpretations of FMVSS No. 108 and permit original equipment installation of “emergency warning lights.” Alternatively, you ask that NHTSA issue guidance regarding the circumstances under which such lighting may be installed by vehicle manufacturers or repair businesses without violating the “make inoperative” provision of the National Traffic and Motor Vehicle Safety Act (Safety Act) (49 U.S.C. §§ 30101 et seq.). 

In responding to this request, NHTSA notes that the contents of this letter do not have the force and effect of law and are not meant to bind the public in any way. This letter is only intended to provide clarity regarding existing requirements under the law at the time of signature. 

After carefully considering your letter, we reaffirm our previous interpretations that, under current law, “emergency warning lights” may not be installed as original equipment and that persons subject to the make inoperative provision of the Safety Act may not legally install the lamps as original or aftermarket equipment. We explain our reasoning below, based on our understanding of the information you present. 

Background 

FMVSS No. 108 specifies requirements for original and replacement lamps, reflective devices, and associated equipment. For auxiliary lamps, the primary restriction imposed by FMVSS No. 108 is in S6.2.1, which states that “[n]o additional lamp, reflective device, or other motor vehicle equipment is permitted to be installed that impairs the effectiveness of lighting equipment required by this standard.” Additionally, both original equipment and aftermarket lighting can run afoul of the “make inoperative” provision, and NHTSA considers the installation of an aftermarket lamp to violate the “make inoperative” provision if the installation of the same lamp as original equipment would violate FMVSS No. 108.1 Whether there is an impairment is determined in the first instance by the manufacturer of the vehicle (or the entity installing the aftermarket lighting) when it is certified as compliant with FMVSS No. 108. NHTSA may contest such a determination if it is clearly erroneous.2 These prohibitions bar installation by a manufacturer, distributor, dealer, rental company, or motor vehicle repair business of lamps that would impair the effectiveness of required lighting, but do not apply to the owner of a vehicle. 

Typically, the impairment determination is made on a case-by-case basis and considers several characteristics of the auxiliary lamp, such as the brightness, color, location, and activation pattern of the lamp, to analyze whether it impairs the effectiveness of required lighting. This list of characteristics is not exhaustive and other considerations may be relevant to the analysis. NHTSA has long maintained that highway traffic safety is enhanced by the drivers’ familiarity with established lighting schemes, which enables them to instantly recognize the meaning the lamps convey and respond accordingly. NHTSA has long interpreted FMVSS No. 108 to require that all auxiliary lamps be “steady burning,” with the sole exception of auxiliary lamps that supplement required lamps that flash, such as turn signals.3 

Discussion 

NHTSA’s longstanding interpretation of FMVSS No. 108 is that the standard does not permit the “emergency warning lights” to be installed as original equipment because they are auxiliary lighting that is not steady burning and would impair the effectiveness of required lamps by causing confusion among other drivers about the meaning of required lighting or distracting drivers from required lighting.4 Further, because “emergency warning lights” would impair the effectiveness of required lamps, NHTSA has also determined that entities listed in § 30122 of the Safety Act that install “emergency warning lights” on new or used vehicles would violate the “make inoperative” provision of the Act. 

Notwithstanding those interpretations, you provide various reasons why you believe that “current regulations permit manufacturers to install such supplemental lighting as original equipment.” We respond to your reasons below. 

1 E.g., Letter to Timothy C. Murphy (Nov. 1, 2004), available at https://www.nhtsa.gov/interpretations/gf006332.
2 Letter from John Womack to Larry Grabsky (Nov. 16, 1993), available at https://www.nhtsa.gov/interpretations/9251.
3 See, e.g., Letter to Richard Seoane (June 27, 2024), available at https://www.nhtsa.gov/interpretations/ncc-231121- 001-autoliv-veoneer-spotlight-interpretation-1; and Letter to Paul Schaye (Sept. 9, 2019), available at https://www.nhtsa.gov/interpretations/571108-ama-schaye-front-color-changing-light.
4 Letter to J. Adam Krugh IV (May 22, 2003), available at https://www.nhtsa.gov/interpretations/002769drn (explaining that a flashing or strobing lamp on top of a school bus would impair the effectiveness of required signal lamps by diverting other drivers’ attention and causing confusion). 

Administrative Rewrite of FMVSS No. 108. First, you state that in an administrative rewrite of FMVSS No. 108, NHTSA removed explicit language in the standard that had contained a provision requiring that all lamps be steady burning unless otherwise indicated. You argue that the removal of this provision indicated an intention to loosen the restriction that auxiliary lamps must be steady burning when activated. 

NHTSA had no such intention. The removal of the referenced “steady burning” language in the FMVSS No. 108 administrative rewrite did not change the underlying substantive requirements that had applied to auxiliary lighting. Before it was modified in 2007, FMVSS No. 108 included an explicit requirement that, with the exception of certain types of required lamps (e.g., turn signal lamps), all lamps on a vehicle, including auxiliary lamps, must be steady burning. In 2007, NHTSA implemented an administrative reorganization of FMVSS No. 108 which, among other things, clarified the blanket “steady burning” requirement (and its exceptions) by converting it into specified individual activation requirements for each type of required lamp.5 Although the reorganized rule no longer includes a blanket “steady burning” requirement, NHTSA stated in the preamble to the reorganized rule that its “rewrite of FMVSS No. 108 is considered administrative in nature because the standard’s existing requirements and obligations are not being increased, decreased, or substantively modified.”6 Further, NHTSA continues to believe that flashing auxiliary lamps would impair the effectiveness of required lamps by distracting or confusing other road users and we have continued to restrict flashing or strobing auxiliary lamps since the rewrite except under a few limited circumstances not relevant here.7 Therefore, because the “emergency warning lights” are not steady burning, they would not comply with FMVSS No. 108 and would impair required lighting. 

Motorists are Used to “Emergency Warning Lights.” Second, you state that one of NHTSA’s reasons for disallowing flashing auxiliary lamps—their tendency to divert attention and cause confusion—is no longer valid for “emergency warning lights” because “the use of flashing-amber lighting has become widespread.” You provide no data or information to support this assertion, except to refer to past agency letters which discussed the make inoperative provision as applied to owners installing flashing or strobe lamps on their own vehicles, including a state installing the lamps on state-regulated emergency vehicles. 

We disagree with your assertion that the letters are indicative of the pervasiveness of “emergency warning lights.” The interpretation letters to which you refer do not endorse the installation of flashing or strobe lamps by individuals or declare that the lights do not impair the effectiveness of required lamps. Rather, those letters simply recognize the limits of NHTSA’s authority under the Safety Act to regulate aftermarket lighting equipment. The agency made, and continues to make, no determination as to whether the flashing amber lights are “widespread.”

5 72 FR 68234 (Dec. 4, 2007).
6 Id.
7 These exceptions include auxiliary lamps that supplement required flashing lamps like turn signals. See Letter to Jerry Koh (Feb. 6, 1986), available at https://www.nhtsa.gov/interpretations/86-250; see also Letter to Lt. Col. Steve Flaherty (May 2, 2003), available at https://www.nhtsa.gov/interpretations/flaherty (deference to states applies to “the installation and use of emergency lighting devices on [undercover state police] vehicles”). 

NHTSA has long believed that flashing amber lighting can unduly divert driver attention and cause confusion among drivers, even among those who have seen them before. As we have stated, “traffic safety is enhanced by the familiarity of drivers with established lighting schemes, which facilitates their ability to instantly and unhesitatingly recognize the meaning lamps convey and respond to them.”8 Flashing amber lighting, except for turn signal lamps, is not “an established lighting scheme” within the context of FMVSS No. 108. The meaning of flashing lights can vary depending on the nature of the vehicle on which they are installed, the context in which they are used, and state or local laws. Motorists might not know if the flashing amber lamps are meant to signal the presence of the vehicle for general driver awareness or the need for drivers to yield the right-of-way or perform some other driving task. The use of flashing amber lights is not sufficiently established and standardized to avoid unduly diverting driver attention or causing confusion. Thus, we continue to believe these lights impair required lighting equipment.9 

Other Federal Regulations and State Laws Recognizing “Emergency Warning Lights.”
Finally, you argue that permitting flashing amber auxiliary lamps as original equipment would “harmonize” NHTSA’s requirements with Federal Motor Carrier Safety Administration (FMCSA) regulations and state laws. You state that an FMCSA regulation (49 C.F.R. § 393.25(e)) permits the use of flashing lights on several vehicle types and that a change in NHTSA’s approach would better ensure such lighting is properly wired and installed. We are also aware of exemptions granted by FMCSA permitting certain entities to use pulsating brake-activated amber lights as well as the operation of commercial motor vehicles equipped with the Intellistop device.10 

Our longstanding interpretation of FMVSS No. 108 regarding flashing auxiliary lights is not impacted by these FMCSA regulations, exemptions, or state laws. The FMCSA regulation does not require the flashing lamps to be installed as original equipment or by an entity subject to the make inoperative provision. Additionally, although you allude to safety concerns about owners improperly wiring or installing emergency warning lights on their vehicles to comply with state laws, we are not aware of any state laws requiring installation of these lights specifically as original equipment or by an entity subject to the make inoperative requirement. Nor is allowing installation by such entities necessary to address improper owner installations of these lights. 

If you have further questions, please contact Eli Wachtel of my staff at (202) 366-2992.

Sincerely,
ADAM RAVIV
Adam Raviv Chief Counsel
 

Dated:12/13/24
Ref: Standard No. 108

8 Letter to J. Adam Krugh IV (May 22, 2003), available at https://www.nhtsa.gov/interpretations/002769drn.
9 Nothing in this letter is intended to conflict with our interpretation, stated in our May 2, 2003, Letter to Lt. Col. Steve Flaherty, that deference to states applies to “the installation and use of emergency lighting devices on [the state’s] vehicles.” Letter available at https://www.nhtsa.gov/interpretations/flaherty.
10 List of FMCSA exemptions in effect available at https://www.fmcsa.dot.gov/exemptions.

ID: NCC-241028-001 Interp Response - Volvo Trucks - FMVSS 121 Air Brake Reservoirs 01.16.2025

January 16, 2025

Mac Bradley Principal Engineer 

Volvo Group Trucks Technology 

Volvo Group North America LLC 

7900 National Service Road 

Greensboro, NC 27409

Re:    Interpretation of Air Brake System reservoir requirements under Standard No. 121 

Dear Mr. Bradley: 

This responds to your letter dated May 23, 2018, on behalf of Volvo Group North America LLC regarding the air brake system reservoir requirements in Federal Motor Vehicle Safety Standard (FMVSS) No. 121, S5.1.2. You describe a technology where an air dryer feeds the service reservoir directly, without the use of a separate supply reservoir or a condensate drain valve. You asked whether technology that you find to be “demonstratively more effective than a supply reservoir or automatic drain valve” may be used to comply with S5.1.2’s requirements. This letter responds to that request. 

In responding, the National Highway Traffic Safety Administration (NHTSA) notes that the contents of this letter do not have the force and effect of law and are not meant to bind the public in any way. This letter is only intended to provide clarity regarding existing requirements under the law at the time of signature. 

Section 5.1.2 requires that each truck and bus shall have:  

One or more service reservoir systems, from which air is delivered to the brake chambers, and either an automatic condensate drain valve for each service reservoir or a supply reservoir between the service reservoir system and the source of air pressure. 

S5.1.2 provides explicit reservoir requirements. Without either an automatic condensate drain valve or a supply reservoir, a vehicle would not comply with S5.1.2. The air dryer technology you suggest includes neither a condensate drain valve nor a supply reservoir. Although you suggest that this new technology is at least equally effective at removing water from compressed air, the standard is specific in its equipment requirements. We cannot by interpretation remove the requirements set forth in express terms in the regulatory text.1 

1 See, e.g., Letter to R.W. Hildebrandt, Bendix Corp. (May 30, 1980), available at www.nhtsa.gov/interpretations/nht80-241 (finding non-compliance where the air brake system may comply with the alleged intent of FMVSS No. 121 but does not comply with the standard’s technical requirements). 

The Notice of Proposed Rulemaking you cited from 1996 did propose revising FMVSS No. 121 to require a means of automatically removing moisture and contaminants from the air system and to delete the requirement for a supply reservoir. See 61 F.R. 56652 (Nov. 4, 1996). However, after consideration, NHTSA terminated that rulemaking, opting for further study of the requirements and test procedures for air drying and cleansing equipment used in air brake systems. See 63 F.R. 14674 (May 26, 1998). 

NHTSA cannot amend its regulations by interpretation. The appropriate vehicle to present your arguments would be a petition for rulemaking to amend FMVSS No. 121. In such a petition, you would be free to rely on the data you shared regarding the efficacy of air dryers at removing water from compressed air in support of a such petition for rulemaking. 

I hope this information is helpful. If you have any further questions, please feel free to contact Evita St. Andre of my staff at this address or (617) 494-2767. 

Sincerely,
ADAM RAVIV

Adam Raviv Chief Counsel
 

Dated: 1/16/25
Ref: Standard No. 121

ID: NCC-230420-001 571.108 Angelina Twardawa Auxiliary Side Lamps Interpretation signed

April 16, 2025

U.S.Department of Transportation
National Highway Traffic Safety Administration
Office of the Chief Counsel
1200 New Jersey Avenue SE. Washington, DC 20590

Ms. Angelina Twardawa 4550 Gustine Ave
St. Louis, MO  63116
angelina@angiestrans.com 

Dear Ms. Twardawa: 

This responds to your letter, received December 5, 2022 in which you requested a letter of interpretation asking whether aftermarket auxiliary trifunctional side marker lights which illuminate red in the rear, amber in the side, and white in the front, and that attach to the rear of a 53-foot trailer on both sides are compliant with Federal Motor Vehicle Safety Standard (FMVSS) No. 108, Lamps, reflective devices, and associated equipment. We apologize for the delay in responding to your inquiry. Based on the information you provided in your letter, we have concluded that installing the device as described may conflict with FMVSS No. 108. However, an alternative color configuration should be permissible under that standard. 

Please note that our guidance below is based on our understanding of the specific information provided in your letter. The contents of this letter do not have the force and effect of law and are not meant to bind the public in any way. This letter is only intended to provide clarity regarding existing requirements under the law at the time of signature. 

Background 

NHTSA is authorized by the National Traffic and Motor Vehicle Safety Act (Safety Act, 49 U.S.C. Chapter 301) to issue FMVSS that set performance requirements for new motor vehicles and new items of motor vehicle equipment. The Safety Act requires manufacturers to self-certify that their vehicles and equipment conform to all applicable FMVSS in effect on the date of manufacture.
NHTSA also investigates safety-related defects. After first purchase of a motor vehicle or item of motor vehicle equipment other than for resale, section 30122 of the Safety Act requires that a manufacturer, distributor, dealer, rental company, or motor vehicle repair business not knowingly make inoperative any part of a device or element of design installed on or in a motor vehicle or motor vehicle equipment in compliance with an applicable motor vehicle safety standard. This letter represents NHTSA's opinion concerning whether your design, as you describe it, would be permitted under FMVSS No. 108 and section 30122.

In your letter, you state that the device is a trifunctional light that attaches to the side of the rear guard of a 53-foot trailer on both sides with an open-ended connector. The lights have a red light designated at the rear, amber light designated at the side, and a white light designated at the front. You note that the piece that attaches to the trailer is rubber and flexible so it will not break, and that the device is stationary. You state the purpose of the device is to assist drivers with backing up, lane changes, and other maneuvers by providing increased visibility of the trailer at night. You ask whether the described design is permitted (both with regards to the device overall and the described lighting configuration), and if it is how far the devices can extend. 

FMVSS No. 108 specifies requirements for original and replacement lamps, reflective devices, and associated equipment, including for trailers. For auxiliary lamps, the primary restriction imposed by FMVSS No. 108 is by S6.2.1, which states that "[n]o additional lamp, reflective device, or other motor vehicle equipment is permitted to be installed that impairs the effectiveness of lighting equipment required by this standard." Additionally, both original equipment and aftermarket lighting can run afoul of the "make inoperative" provision in 49 U.S.C. § 30122. These prohibitions bar installation by a manufacturer, distributor, dealer, rental company, or motor vehicle repair business of lamps that would impair the effectiveness of required lighting, but do not apply to the owner of a vehicle. We note that whether there is an impairment is determined in the first instance by the manufacturer of the vehicle (or the entity installing the aftermarket lighting) when it is certified as compliant with FMVSS No. 108. 

Typically, the impairment determination is made on a case-by-case basis and looks at four main characteristics of the auxiliary lamp to analyze whether it impairs the effectiveness of required lighting. These are the brightness (photometric intensity), color, location, and activation pattern of the lamp.1 This list is not exhaustive and other considerations may be relevant to the analysis. NHTSA has long stated that highway traffic safety is enhanced by the familiarity of drivers with established lighting schemes, which facilitates their ability to instantly recognize the meaning the lamps convey and respond accordingly.2 Therefore, we have long interpreted the impairment provision to prohibit auxiliary lamps that are colors which are likely to cause confusion to other road users.3 Additionally, auxiliary lamps must be located such that they would not interfere or be confused with the lamps required by our standards. For example, we have stated that two auxiliary 

1 This letter is limited to the information provided in your request. Your request did not state the activation pattern or intensity of the device, which can be relevant to determining if a device causes impairment. For the purposes of this letter, we assume without finding that these aspects of your device do not cause impairment. The following information is provided for your reference regarding these elements. Regarding activation pattern, NHTSA interprets FMVSS No. 108 to require that all auxiliary lamps be "steady burning," with the sole exception being auxiliary lamps that supplement required lamps that flash, such as turn signals. Letter to Paul Schaye (Sept. 9, 2019), available at htqJs://www.nhtsa.gov/interpretations/571108-ama-schaye-front-color-changing-light. Regarding intensity, NHTSA interprets the impairment provision to prohibit auxiliary lamps that are so bright as to obscure or distract from a vehicle's required lamps. For example, NHTSA has in the past stated that supplemental lighting can impair the effectiveness of the required lighting if it is so intense that it glares other road users or masks required signal lamps. See Letter to Rusty Riggin, Aug. 2, 2002, available at htqJs://www.nhtsa.gov/interpretations/24179ztv, (explaining that a supplemental rear cornering lamp could violate the impairment provision if it was so intense that it "create[d] distracting glare"). Letter to Mark Wallach (Oct. 17, 2006) available at htqJs://www.nhtsa.gov/interpretations/wallach3.
2 Letter to Robert Clarke (July 28, 2005), available at htqJs://www.nhtsa.gov/interpretations/gID0255l3.
3 As an example, for auxiliary lamps located on the front of vehicles, these colors include red, which could be confused for a taillamp or stop lamp, and green, which typically conveys the message that one may proceed forward and could therefore impair required lighting that indicates caution. Letter to Paul Schaye (Sept. 9, 2019), available at htqJs://www.nhtsa.gov/interpretations/571108-ama-schaye-front-color-changing-light See also, Letter to Kerry Legg (Oct. 19, 2006), available at htqJs://www.nhtsa.gov/interpretations/leggl.

lamps located next to the three-lamp trailer identification lamp cluster would detract from the purpose of the cluster.4    '

For lighting relevant to your inquiry, FMVSS No. 108 requires that trailers have two amber side marker lamps as far to the front as practicable and two red side marker lamps as far to the rear as practicable. Trailers 30 feet or longer must also have amber intermediate side marker lamps and reflex reflectors on each side located at or near the midpoint between the front and rear side marker lamps.5, 6 

Discussion 

We now turn to your inquiry. Your lamp is not required equipment, and you correctly observe that it is auxiliary or supplemental lighting.7 Therefore, we turn to the question of impairment and look to the characteristics discussed. The factors which appear most relevant to your inquiry are the location and color of the lamps, which we analyze together. Due to the color and location of the lamp as described in your letter, it is likely to impair the effectiveness of the side marker lamps required to be installed on trailers by FMVSS No. 108, and, if installed by you or another entity subject to the "make inoperative" prohibition as aftermarket equipment, could make inoperative lighting required by FMVSS No. 108.8 However, an alternative color scheme would be permissible under FMVSS No. 108. 

Regarding side marker lamps, FMVSS No. 108 requires that intermediate side marker lamps be amber, and rear side marker lamps be red. Your design notes that your device will be mounted at the rear and that the side of the device will have amber lights. Therefore, in driving conditions
with poor visibility, such as at night or in heavy weather, your device may impair the effectiveness of the required intermediate side marker lamps by confusing nearby drivers about whether it indicates the rear or middle of the trailer, which could lead to unsafe driving decisions. 

4 Letter to Robert Clarke (July 28, 2005), available at htt;ps://www.nhtsa.gov/inter_pretations/gf00255l3.
5 We also note that S6.l.3.l of FMVSS No. 108 requires that each lamp, reflective device, and item of associated equipment must be securely mounted on a rigid part of the vehicle. The purpose,of this requirement is to ensure that lamps and reflectors do not sway in the wind on rigid hinges or flexible mud flaps when the vehicle is in motion. Letter from Frank Burndt to Dietmar K. Haenchen, (date unavailable), available at https://www.nhtsa.gov/inter_pretations/aiam3320. S6.l.3.1 is organized in S6.1 ofFMVSS No. 108, which contains requirements applicable to required lamps, reflective devices, and associated equipment. Although this provision does not explicitly apply to auxiliary lamps, an auxiliary device that is not securely mounted to a rigid part of the vehicle may impair the effectiveness ofrequired lighting because the motion of the light could distract drivers.  We have assumed for the purposes of this letter that your device is securely mounted to a rigid part of the vehicle and encourage you to ensure that this is the case.
6 49 CFR 571.108 Table 1-b. 49 CFR 393.11, which you referenced in communication with my staff, which requires commercial motor vehicles operated by motor carriers to be equipped with such lighting, contains similar specifications for color and placement of side marker lamps.
7 Your request describes your device as a "side marker lamp." Side marker lamps are a type of required equipment under FMVSS No. 108. Because your device is not required lighting, to avoid confusion this letter does not refer to your device as a side marker lamp.
8 Section 30122 applies to any "manufacturer, distributor, dealer, rental company, or motor vehicle repair business." We assume, for the purposes of this letter, that you are subject to this provision. 

Our opinion is based on the location and color of the lights as described in your letter. An alternative color scheme, with a red light facing the side in place of the amber light, is unlikely to have the same risk of impairing the effectiveness of the side marker lamps because it would
correspond to the color required for the required side marker lamps installed on each side as far to the rear as practicable, close to where you plan to install the device. We also encourage you to consider designs which mitigate any risk that a forward-facing white light could be perceived as a headlamp by other road users. 

Finally, you inquired about how far out the devices may extend from the trailer. NHTSA's regulations do not contain requirements specific to this question. Vehicle width is regulated by the Federal Highway Administration, who's regulation states that no State shall impose a width limitation of more or less than 102 inches (except Hawaii) for vehicles operating on the National Network.9 Five items are excluded regardless of how far they extend beyond the exterior of vehicles; rear view mirrors, turn signal lamps, handholds for cab entry/egress, splash and spray suppressant devices, and load induced tire bulge. Other excluded devices are: all non-property carrying devices or components at the front of a semitrailer or trailer, devices that do not extend more than 3 inches beyond each side or the rear of a vehicle, devices needed for loading or unloading that do not extend more than 24 inches beyond the rear of the vehicle, and aerodynamic devices that do not extend more than 5 feet beyond the rear of a vehicle, provided they have neither the strength, rigidity nor mass to damage a vehicle that strikes a trailer so equipped from the rear and provided also that they do not obscure tail lamps, turn signals, marker lamps, identification lamps, or any other required safety features, such as hazardous materials placards or conspicuity markings.10 

We also note that, because it is an item of motor vehicle equipment subject to the requirements of the Safety Act, it must be designed free from defects regarding motor vehicle safety. Additionally, truck tractors and trailers operated commercially in interstate commerce are subject to the regulations of the Federal Motor Carrier Safety Administration (FMCSA). Finally, States may have laws applicable to certain motor vehicle lighting. We are unable to advise you on those laws, but you should ensure your system complies with any and all applicable State laws.

We hope you find this information helpful. If you have further questions, please contact Eli Wachtel of my staff at (202) 366-2992.

Sincerely,

Peter Simshauser Chief Counsel

Dated: 4/16/25
Ref:  Standard No. 108
 

9 23 CFR 658.15.
1°FHWA Vehicle Size and Weight Q&A, available at https://ops.fhwa.dot.gov/freight/sw/fags/qa.cfin?categ01y=8. For
more excluded devices, see 23 CFR 658.16 and Appendix D to 23 CFR 658.

ID: NCC-230607-001 571.108 Automatic Activation of Hazard Warning Signal for Nonresponsive Driver Frooshani signed 7.22.25

U.S. Department of Transportation
National Highway Traffic Safety Administration
Office of the Chief Counsel
1200 New Jersey Avenue SE. Washington, DC 20590

July 22, 2025

Mr. John Frooshani 

Vehicle Regulatory Manager, Government Relations  

North American Subaru, Inc. 

One Subaru Drive Camden NJ 08103 

Dear Mr. Frooshani,

I write in response to your letter dated February 5, 2020, requesting an interpretation on whether identified advanced driver assistance system (ADAS) features would comply with the hazard warning signal requirements in Federal Motor Vehicle Safety Standard (FMVSS) No. 108; Lamps, reflective devices, and associated equipment. You also spoke with staff from the National Highway Traffic and Safety Administration's (NHTSA) Office of the Chief Counsel on October 29, 2024. You ask whether your system, after determining a driver is non-responsive, could automatically activate the vehicular hazard warning signal while decelerating the vehicle and bringing it to a stop. Our conclusion is that such a system is permissible in the circumstances described in your letter. 

The contents of this interpretation letter do not have the force and effect of law and are not meant to bind the public in any way. This letter is only intended to provide clarity regarding existing requirements under the law at the time of signature. 

Background 

NHTSA is authorized by the National Traffic and Motor Vehicle Safety Act (Safety Act, 49 U.S.C. Chapter 301) to issue FMVSS setting performance requirements for new motor vehicles and new items of motor vehicle equipment. NHTSA does not pre-approve new motor vehicles, new motor vehicle equipment, or new motor vehicle technologies. In addition, NHTSA does not prohibit the introduction of new motor vehicles or motor vehicle technologies such as Automated Driving Systems (ADS) into the vehicle fleet, provided those vehicles and technologies meet applicable FMVSS and do not present a safety defect. The Safety Act requires manufacturers to self-certify that their vehicles and equipment conform to all applicable FMVSS in effect on the date of manufacture. 

Two provisions of FMVSS No. 108 bear on the issue raised in your letter. First, the standard requires vehicles, except trailers and motorcycles, to be equipped with a vehicular hazard warning signal operating unit and a vehicular hazard warning signal flasher.1 A vehicular hazard warning signal operating unit is defined as a driver-controlled device which causes all required tum signal lamps to flash simultaneously to indicate to approaching drivers the presence of a vehicular hazard.2,3 Second, FMVSS No. 108 S6.2.1 states that no additional lamp, reflective device, or other motor vehicle equipment is permitted to be installed that impairs the effectiveness of lighting equipment required by FMVSS No. 108.4 

Your letter states that Subaru is exploring deploying an ADAS with a feature intended to prevent a crash if a human driver has become nonresponsive, with the system assuming vehicular control when a driver is inattentive and non-responsive to system warnings. In the described scenario, the vehicle would be brought to a stop and would "activate the hazard warning lamps as the vehicle is decelerating and continue to activate the hazard lamps after the vehicle has been brought to a stop." You state that, in your opinion, the scenario described in your letter is like the one in our 2016 letter to Brian Latouf of General Motors, which allowed automatic activation of the hazard signal following detection of a nonresponsive driver and after the vehicle has been brought to a stop by advanced vehicle systems, and you seek our concurrence. 

Discussion 

NHTSA's interpretations of "vehicular hazard warning signal operating unit" read FMVSS No. 108 as broadly restricting automatic activation of the hazard signal.5 However, NHTSA historically has read FMVSS No. 108 to allow automatic activation on a case-by-case basis under limited circumstances consistent with the purpose of the hazard warning signal stated in
the standard. FMVSS No. 108 does not permit automatic hazard signal activations that lack any relationship to the original purpose of a hazard warning signal or could create confusion about the signal's meaning.6 

1 49 C.F.R. § 571.108.
2 Id. When activated, sufficient turn signals must flash to meet the minimum photometric requirements in FMVSS No. 108 applicable to turn signals. For the purposes of this letter, we refer to these systems collectively as activating the "hazard signal."
3 Id. The standard also defines the vehicular hazard warning signal flasher as a device which, as long as it is turned on, causes all the required turn signal lamps to flash. This system must flash when actuated by the operating unit. See id Table I-a.
4 49 C.F.R. § 571.108 S6.2. l. Under the impairment analysis NHTSA typically considers four aspects of supplemental lighting: activation pattern, brightness, color, and lamp location. In addition, the impairment analysis is applicable to supplemental lighting (i.e., lighting not required by the standard) and is closely related to the requirement that a manufacturer not "knowingly make inoperative" a compliant device or element of design. 49
U.S.C. § 30122(b). See, e.g. Letter to Paul Schaye, Feb. 9, 2019, available at
https://www.nhtsa.gov/inter.pretations/571108-ama-schaye-front-color-changing-light.
5 In letters to Mark Steele and Eric Reed in 1999 and 2000, NHTSA interpreted "a driver controlled device," to mean that that the hazard signal may not automatically activate. See Letter to Mark Steele, Feb. 25, 2000, available at https://www.nhtsa.gov/inter.pretations/2ll7lztv : and Letter to Eric Reed, Feb. 29, 2000, available at https://www.nhtsa.gov/inter.pretations/reedztv. 
6 Letter to Sen. Orrin G. Hatch, Aug. 5, 1999, available at https://www.nhtsa.gov/inter.pretations/20l80ztv. 

Per FMVSS No. 108, the purpose of the hazard warning system is "to indicate to approaching drivers the presence of a vehicular hazard." Recent interpretations have noted that "the purpose of the hazard warning is to indicate to approaching drivers that the vehicle is stopped or is proceeding at a slower rate than surrounding traffic."7 Several previous agency interpretations referenced FMVSS No. 108 S6.2.1 and emphasized that there is no ambiguity about the meaning or purpose of the hazard signal following a crash.8 Although S6.2.1 applies only to equipment not required by FMVSS No. 108, in our 2016 letter to Mr. Latouf, we clarified that the same analysis applies to automatic activation of the hazard signal.9,10 

Several letters of interpretation have discussed situations in which we believe automatic activation of the hazard signal would be inconsistent with FMVSS No. 108, such as during braking events,11 after "sudden release of the accelerator pedal,"12 or as a "deceleration warning system"13 where it would conflict with the purpose of the stop lamps.14 Most recently, on March 22, 2023, NHTSA denied a petition for decision of inconsequential noncompliance filed by

7 Letter to Brian Latouf, Nov. 18, 2016. https://www.nhtsa.gov/interpretations/16-1289-gm-hazard-innovative-28-apr-16-rsy. This statement is based on a previous statement made in our letter to Sen. Richard Lugar on May 9, 2000, that drivers in general activate the hazard signal to "indicate either that [they are] proceeding at a slower rate than surrounding traffic, or that the vehicle is stopped on or off a roadway." https://www.nhtsa.gov/interpretations/21478ztv. This was a description of typical hazard signal use and was not intended to state the purpose of the hazard warning. The letter stated the activation should depend on the driver's evaluation of the driving environment and should not occur involuntarily simply because the vehicle is decelerating. 8 Letter to Mark Steele, Feb. 25, 2000, available at https://www.nhtsa.gov/interpretations/2ll71ztv ; Letter to Timothy Bartlett, Jan. 28, 2002, available at https://www.nhtsa.gov/interpretations/23695ztv; Letter to Stephen Powers, Jan. 19, 2021, available at https://www.nhtsa.gov/interpretations/571108-help-system-powers.
9 Letter to Brian Latouf, Nov. 18, 2016, available at https://www.nhtsa.gov/interpretations/16-1289-gm-hazard­ innovative-28-apr-16-rsy. This conclusion is based in part on our longstanding position that the "use of required lighting equipment for other than its original purpose" constitutes equipment not required by the standard such that it can result in impairment. See, e.g. Letter to Sen. Orrin G. Hatch, Aug. 5, 1999, available at https://www.nhtsa.gov/interpretations/20180ztv. Automatic activation could be understood as allowed supplemental lighting (in addition to the manually controlled hazard signal) if the specific system does not impair the effectiveness of any required lighting. Because it does not influence our conclusion in this letter, we do not determine whether automatic activation of the hazard signal in the manner you describe is or is not supplemental lighting or other motor vehicle equipment.
10 NHTSA interprets FMVSS No. 108 to require that all auxiliary lamps be "steady burning," with the sole exception being auxiliary lamps that supplement required lamps that flash, such as turn signals. Letter to Donald Lane, Nov. 6 2024, available at https://www.nhtsa.gov/interpretations/ncc-230120-001-571108-peterson-trailer­ auxiliary-door-light-110624-signed. To the extent that the lighting described here could be considered supplemental lighting, NHTSA would view it as supplementing required lights that flash.
11 Daimler Trucks North America, LLC, Denial of Petition for Decision of Inconsequential Noncompliance, 88 Fed. Reg. 17291 (Mar. 22, 2023).
12 Letter to David Coburn, Aug. 6, 1999, available at https://www.nhtsa.gov/interpretations/19886ztv.
13 Letter to Jeffrey Echt, incoming received Mar. 10, 1995, available at https://www.nhtsa.gov/interpretations/aiam552l. Automatically activating the hazard signal can also interfere with other required lighting, such as the turn signals. We have also addressed cases in which other vehicle systems were activated. See, e.g. Letter to Sen. Orrin G. Hatch, Aug. 5, 1999, available at https://www.nhtsa.gov/interpretations/20l80ztv (finding activating the hazard warning system when the horn is sounded would impair the hazard warning system).
14 See Letter to Stephen Powers, Jan. 19, 2021, available at https://www.nhtsa.gov/interpretations/571108-help ­
system-powers (limiting the automatic activation of the specified system to after a crash in part because it activated the turn signals up to three times faster than the required flash rate under FMVSS No. 108). 

Daimler Trucks North America, LLC (DTNA), regarding certain Model Year 2020-2021 Freightliner Cascadia heavy trucks.15 These trucks contained a system that automatically activated the hazard signal during a brake assist application, when the brake system applies maximum braking force to assist the driver in bringing the truck to a complete stop. 

In contrast to these scenarios, our 2016 letter to Mr. Latouf addressed a similar situation to the one described in your letter. There, we stated that under FMVSS No. 108 a system could, after finding a driver unresponsive and bringing the vehicle to a stop, automatically activate the hazard signal.16 We analogized the situation to the one after a crash and noted that being at a complete stop "is the prototypical situation in which the hazard lights are intended to be used, and it is one of the situations that other motorists have come to expect when they see the hazard signal."17 However, we also stated that "the purpose of the hazard warning is to indicate to approaching drivers that the vehicle is stopped or is proceeding at a slower rate than surrounding traffic."18 We also declined to state that such activations could occur only when stopped, finding that future approaches for automatic activation of the hazard signal would be handled on a case­ by-case basis.19 

Based on our understanding of the specific circumstances described in your letter, the automatic activation of the hazard warning signal you describe is permissible under FMVSS No. 108. As an initial matter, because FMVSS No. 108 does not specify in what situations the hazard warning signal may or may not be activated, we decline to state categorically that the hazard warning signal can be automatically activated only after a vehicle has come to a complete stop. Indeed, in the letter to Mr. Latouf, we acknowledged that "proceeding at a slower rate than traffic" is a situation in which drivers typically activate the hazard warning system. 

Where past agency interpretations have opined negatively about in-motion activations, it was because the use in question was not consistent with the purpose of the hazard warning system or it impaired the effectiveness of required lighting in violation of FMVSS No. 108.20 However, your system does not appear to activate the hazard warning system in a way that we have previously found unacceptable. Instead, we view the conditions described in your letter as largely similar to those described in our letter to Mr. Latouf. 

This letter does not mean that NHTSA views FMVSS No. 108 as generally allowing the automatic use of the hazard warning signal while in motion or to indicate that a vehicle's ADAS 

15 88 Fed. Reg. 17291. We believe the circumstances of the petition are distinguishable under FMVSS No. 108. First, Subaru's system does not adjust the flash rate. Second, it activates only in the rare event of a nonresponsive driver. Third, DTNA's system specifically activated during brake events. FMVSS No. 108 states that the stop lights communicate that a vehicle is stopping or diminishing speed by braking. Therefore, the instant circumstance presents much lower risk of confusion than activation during a brake assist.
16 Letter to Brian Latouf, Nov. 18, 2016, available at https://www.nhtsa.gov/intei:pretations/16-1289-gm-hazard ­
innovative-28-apr-16-rsy.
17 Id
18 Id See Supra, note 9, for clarification regarding this quote.
19 Id
20 This letter does not rescind prior NHTSA letters of interpretation on the topic of automatic activation of the hazard warning system. 

or ADS systems are active. The presence of a nonresponsive driver creates a situation where vehicle operation and driving maneuvers are largely disabled and will be for an unknown duration, as is often true following a crash or if there is a health or mechanical issue. In such a circumstance, even if the vehicle is being decelerated to a stop, the hazard warning is not being used to communicate deceleration, activation of the stop lamps, or another action that may be the purview of a lamp required by FMVSS No. 108. Instead, the activation occurs only upon the detection of a separate hazard: a nonresponsive driver. Therefore, the risk of ambiguity or confusion of the signals is low. 

Conclusion 

Based on the information presented in your letter, the system described above would not violate FMVSS No. 108's requirements applicable to the vehicular hazard warning signal operating unit or vehicular hazard warning signal flasher. It would also not impair the effectiveness of required lighting. This interpretation is specific to the circumstances described above.

We note that Subaru indicates that when the driver is unable or unwilling to take control of the vehicle, the system will bring the vehicle to a stop. A vehicle system that stops a vehicle directly in a roadway might, depending on the circumstances, be considered to contain a safety-related defect, i.e., it may present an unreasonable risk of an accident occurring or of death and injury in an accident.21 Federal law requires the recall of a vehicle that contains a safety-related defect.22 We urge Subaru to fully consider the likely operation of the system it is contemplating and ensure that it will not present such a risk. 

Finally, activation of the hazard signal is subject to State laws, which may control when a hazard signal may be used. Nothing in this interpretation should be read to preempt State law regarding when it is appropriate for a hazard warning system to be used. We are unable to advise you on those laws, but you should ensure your system complies with any and all State laws regarding when a hazard warning system may be activated.
If you have any further questions, please contact Eli Wachtel of my staff at interpretations.NHTSA@dot.gov. 

Sincerely,

Peter Simshauser 

Chief Counsel

Dated: 7/22/25
Ref: Standard No. 108

2149 u.s.c. §§ 30102, 30118.
22 49 U.S.C. § 30118.