Mr. Yoshiaki Matsui
Automotive Equipment
Legal & Homologation Section
Stanley Electric Co., Ltd.
2-9-13, Nakameguro, Meguro-ku
Tokyo 153, Japan

Re: Headlamp System Containing Fog Lamp

Dear Mr. Matsui:

This replies to your letter of August 11, 1995, with reference to possible headlamp systems that produce a fog lamp beam, as well as upper and lower beams. According to your letter, "the fog lamp is reciprocally incorporated with the high beam headlamp, using one dual-filament bulb (ex.; HB2). The high beam and the fog lamp will not be lit simultaneously." You refer to paragraph S5.1.3 of Federal Motor Vehicle Safety Standard No. 108 and conclude that "such a combination will not impair the effectiveness of the headlamp."

We agree, with respect to the headlamp itself, that a fog lamp operating simultaneously with the lower beam will not impair the effectiveness of the lower beam's photometrics and ability to illuminate the roadway. We view this as a supplement to the lower beam. However, under S5.1.3, the question is whether the fog lamp, either operating alone or when the lower beam headlamp is activated, will impair the effectiveness of any front lighting equipment that is required by Standard No. 108. The responsibility for the determination of compliance with S5.1.3 is not Stanley's, but that of the manufacturer of the vehicle in which the combination headlamp is installed, who must certify that its vehicle meets all applicable U.S. Federal motor vehicle safety standards.

The other front lighting equipment required by Standard No. 108 consists of parking lamps and turn signal lamps. The amber parking lamps serve to mark a vehicle, a function incidentally served by white fog lamps. Thus we do not believe that the Stanley headlamp would impair the effectiveness of parking lamps in any position in which the headlamp may be installed on the front of a vehicle.

The situation differs with respect to turn signal lamps. A vehicle manufacturer must take care to ensure that a vehicle on which the combination headlamp is installed conforms to the requirements of Standard No. 108 and to paragraph of SAE Standards J588 NOV84 or J1395 APR85, the two turn signal standards incorporated by reference in Standard No. 108. Paragraph treats the relationship between luminous intensity and photometrics "where the front turn signal is mounted in close proximity to the low beam headlamp or any additional lamp used to supplement or used in lieu of the low beam, such as an auxiliary low beam or fog lamp." It does this by establishing luminous intensity multipliers based upon the distance that separates the lamps. For example, if the space between the front turn signal and the lighted edge of the fog lamp is 75 mm to less than 100 mm, the photometric requirements for a front turn signal lamp are 1.5 times more than those required when the spacing is 100 mm or more (Paragraph S5.3.1.7 of Standard No. 108 requires the multiplier at this distance to be 2.5 when the lamp is a lower beam headlamp rather than a fog lamp).

Finally, as a cautionary note, we believe that Stanley should evaluate the glare potential of the headlamp when the fog lamp and lower beam are operating simultaneously, as it is important to safety that oncoming drivers not be distracted or discomforted in the operation of their vehicles.

If you have any further questions, you may refer them to Taylor Vinson of this Office (phone: 202-366-5263).


John Womack Acting Chief Counsel ref:108 d:9/20/95