Interpretation ID: nht88-3.12

TYPE: INTERPRETATION-NHTSA

DATE: 08/19/88

FROM: ERIKA Z. JONES -- CHIEF COUNSEL NHTSA

TO: JOSEPH P. FAIA --

TITLE: NONE

ATTACHMT: UNDATED LETTER TO ERIKA Z. JONES FROM JOSEPH P FAIA, OCC - 2177

TEXT: This is in reply to your recent undated letter regarding a vehicle lighting accessory for trucks and trailers. It appears from your letter and enclosed diagram that the purpose of the device is to illuminate "two dimensional displays" on the side or rea r of vehicles. A number of such devices would be required, depending on the size of the display to be illuminated. You have not stated the candlepower of the device. Reference is made to a transparent section through which the light is emitted, and to a "semi-translucent" section which is "tinted and arranged to function as the running lights commonly seen on trailers." The color of the light is not specified, but we shall assume that it is amber or red when emitted through the "semi-translucent" sec tions, and white when emitted through the transparent sections to illustrate the display.

You have asked four questions with regard to this device. The first question is whether it can be used as a "combination side illumination and marker light." As a general rule, supplementary lighting devices such as yours are permissible as original equ ipment if they do not impair the effectiveness of lamps, reflective devices, and associated equipment required by Federal Motor Vehicle Safety Standard No. 108. They are permissible as aftermarket equipment under Federal law if their installation by a p erson other than the vehicle owner does not "render inoperative in whole or in part" lighting equipment installed in accordance with Standard No. 108, but their legality is otherwise determined by the laws of the States in which the vehicle is registered and operated. As for whether your device may be used as a combination side illumination and marker light, if you mean as the only side marker lamp, the combination per se is not prohibited by Standard No. 108. However, the side marker lamp in such a c ombination must comply with photometric, location, color, and other requirements for such lamps, and its effectiveness must not be impaired. One example of impairment would be if the glare from the device's white light masked the conspicuity of the side marker. As a combined device supplementing the required side marker lamp, it is permissible if it does not impair the effectiveness of

the required side marker. For purposes of this letter and with respect to Standard No. 108 we equate "impairment of effectiveness" with "partial inoperative."

Your second question is whether it can be used "as a backup light and parking light, to be used only in these situations." It is unclear whether you intend the device to be the backup lamp required by the standard, or one that supplements it. If the for mer, its use is permissible provided that the backup function meets all requirements of Standard No. 108 that are specified for backup lamps, such as color and photometrics, and provided that the display function does not impair the effectiveness of the backup function. Because the color of light in both functions would be identical, care must be taken to ensure that the backup signal is clearly perceived. If you intend it as a supplementary backup lamp, it is permissible as long as it does not impair the effectiveness of the primary backup lamp. Your term "parking light" is unclear; because front parking lamps are not required on vehicles whose overall width is 80 inches or more, I assume you mean a lamp on the rear of a vehicle that is not a backu p lamp but which can be used to indicate that the vehicle is moving slowly while being parked. The device appears permissible as long as it does not impair the effectiveness of the other lighting equipment on the rear.

Your third question is whether the device may be used as a stop lamp, activated only when the brake is applied. Two devices may be used as the original equipment stop lamps, provided all requirements of Standard No. 108 are met and that the display func tion does not impair the effectiveness of any other lighting equipment. One or more devices could be used as supplementary stop lamps under the same restriction.

Your final question is whether it may be used alone as a display light. The answer is yes, subject to the impairment prohibition. The only specifically prohibited use of the lamp is its combination with a clearance lamp, a configuration which appears d epicted by the uppermost lights, front and rear, of your Figures 2 and 3.

I hope that this answers your question.

Sincerely,