Interpretation ID: 1985-03.27

TYPE: INTERPRETATION-NHTSA

DATE: 08/09/85

FROM: JOHN LOVSTEDT -- HAWAII DOT MOTOR VEHICLE SAFETY OFFICE

TO: JERE MEDLIN -- OFFICE OF RULEMAKING NATIONAL HIGHWAY TRAFFIC SAFETY ADMINISTRATION

TITLE: NONE

ATTACHMT: ATTACHED TO LETTER DATED 11/12/85 FROM ERIKA Z. JONES -- NHTSA TO LARRY HIROHATA, REDBOOK A28, STANDARD 108

TEXT: Dear Ms. Medlin:

We request a clarification to the final rule for modulating headlamps on motorcycles, which was published in the July 22, 1985, Federal Register.

The amendments to 49 CFR 571-108 shall permit the headlamps and side marker lamps to be wired to flash for signalling purposes. Does this mean that the headlamps on any motor vehicle can be wired to operate as a turn signal light in conjunction to general illumination of the area immediately ahead of the vehicle?

We question the requirement because the Society of Automotive Engineers (SAE) standard J580 defines a sealed beam headlamp assembly (J580, Section 2.1) as: "A major lighting assembly which includes one or more sealed beam units used to provide general illumination ahead of the vehicle". Also, SAE standards J588f, entitled, "Turn Signal Lamps" and J1221, entitled, "Headlamp - Turn Signal Spacing", both recommend that the spacing between the turn signal lamp and headlamp lower beam be at least four inches apart.

49 CFR, Section 393.22(b)(1), entitled, "Prohibited Combinations" (Federal Motor Carrier Safety Regulations, Bureau of Motor Carrier Safety) states in part: "A turn signal lamp must not be combined optically with either a headlamp or other lighting devices or combinatin of lighting devices that produces a greater intensity of light than the turn signal lamps."

Hence, we conclude that the headlamps of a motor vehicle should not be wired to incorporate the turn signal system or provide other functions when lamps are required to be illuminated during hours of darkness.

Your prompt response to this request is appreciated. Please send your response to:

Larry Hirohata

Vehicle Equipment Safety Specialist

Department of Transportation

Motor Vehicle Safety Office 79 South Nimitz Highway

Honolulu, Hawaii 96813

Thank you for your consideration.

Yours very truly,