Interpretation ID: nht94-7.46

DATE: March 10, 1994

FROM: John Womack -- Acting Chief Counsel, NHTSA

TO: Joe de Sousa -- President, Safety Pro's International, Inc.

TITLE: None

ATTACHMT: Attached to letter dated 8/12/93 from Joe de Sousa to NHTSA Office of Chief Counsel (OCC-8998) and letter dated 8/12/93 from Joe de Sousa to Richard Van Iderstine

TEXT:

We have received your letter of August 12, 1993, as well as your letter to Mr. Van Iderstine of this agency and its enclosures.

You are interested in marketing an accessory daytime running lamp (DRL) system, and have asked for an interpretation of Federal Motor Vehicle Safety Standard No. 108 as it applies to this product. There appear to be two versions of this system. In both systems, the DRLs are the lower beam headlamps, automatically activated at 77% intensity when the ignition is turned on. The taillamps and side marker lamps are not activated. The systems are deactivated when the ignition is turned off. The systems differ in that one automatically activates the headlamps to full intensity (while activating the taillamps and side marker lamps as well) at a predetermined lower ambient light level.

Under the National Traffic and Motor Vehicle Safety Act, aftermarket lighting equipment may be installed provided that it does not render inoperative, in whole or in part, any device or element of design installed in accordance with a Federal motor vehicle safety standard. The system you describe is congruent with the DRL systems permitted by Standard No. 108, which allows DRLs to be lower beam headlamps operated at less than full intensity, without activation of the taillamps and side marker lamps. Therefore, the installation of either of your DRL systems would not affect a vehicle's pre-existing compliance with Standard No. 108 or any other standard, and is permissible under our regulations.

We note that the reduced intensity is achieved by a "pulse with modulation" which cycle the headlamps "on and off faster than the eye can detect." S5.5.10(d) of Standard No. 108 requires headlamps to be steady-burning for uses other than flashing. While a modulating headlamp technically is not a steady-burning one, for purposes of this requirement we have concluded that there is no failure to conform if the modulating light from the lamp is perceived to be a steady beam, as appears to be the case here.