Interpretation ID: aiam2900
Safety Director
U.S. Army Tank- Automotive Materiel Readiness Command
Department of the Army
Warren
MI 48090;
Dear Mr. Shirock: This is in reply to your letter of November 13, 1978, to th Administrator questioning whether certain trucks procured by your Command comply with paragraph S4.5.4 of Federal Motor Vehicle Safety Standard No. 108.; That paragraph states 'The stop lamps on each vehicle shall b activated upon application of the service brakes.' You wrote that 'when the hazard warning lights are activated the stop lamp cannot be activated upon application of the service brakes.' The system you describe would be in compliance with Standard No. 108, if the stop lamps and signal lamps are optically combined, for the following reason. Paragraph S4.4.1 allows combination of a stop lamp with a turn signal lamp (which provides the hazard warning signal). Paragraph 4.2 of SAE Standard J586c *Stop Lamps*, August 1970 (incorporated by reference in Standard No. 108 as the operative standard for stop lamps) requires that 'When a stop signal is optically combined with the turn signal, the circuit shall be such that the stop signal cannot be turned on in the turn signal which is flashing.; This, of course, means that in a combination lamp the stop signa cannot be given while the hazard warning signal is being operated. If the Army deems it desirable it could require a different circuitry in combination lamps by which the stop lamps and hazard warning signal lamps could operate simultaneously, as military vehicles need not conform to Federal safety standards (49 CFR 571.7(c)).; Because several jurisdictions require slow-moving vehicles to use th hazard lamps while in motion, I am asking our Office of Rulemaking to review this prohibition. Thank you for bringing this matter to our attention.; Sincerely, Joseph J. Levin, Jr. Chief Counsel