Mr. Bart W. Hill
JMH Trailers
233 Far View Road
Hamburg, PA 19526

Dear Mr. Hill:

This is in reply to your letter of June 9, 1999, with respect to the operation of side turn signal lamps on dump bodies that your company manufactures. Thank you for including photos to help us advise you.

You install side turn signal lamps on your products. The wiring on trucks with dump bodies is such that "the side turn also lights when the brakes are applied" (we understand that the side turn signal is steady burning when activated by the brakes). A Pennsylvania state police officer has told your customer that this is illegal. However, the Pennsylvania Department of Transportation ("PennDot")has informed you that it is legal "if it does not violate the Federal standard." Therefore, you have asked whether this configuration does violate the Federal standard.

Federal Motor Vehicle Safety Standard No. 108, Lamps, Reflective Devices, and Associated Equipment, does not require a vehicle to have side turn signal lamps. S5.1.3 of Standard No. 108 prohibits the installation of supplemental lighting equipment if the lamps would impair the effectiveness of lighting equipment that the standard requires. As we see it, the question here is whether the operation of both amber-colored side turn signal lamps in a steady burning mode when the red stop lamps are activated in a steady burning mode can be said to impair the effectiveness of the stop lamps.

The activation of both side turn signal lamps in a steady burning mode is the functional equivalent of an amber supplementary stop lamp that is mounted on the vehicle's side. In our opinion, auxiliary lighting equipment must perform in the same manner, and perform the same function, as the original equipment it is intended to supplement. Standardization of signals is important so that following drivers will not hesitate to respond when the brakes of a vehicle are applied and its stop lamps are activated. The combination of amber side lamps and red rear ones have the potential to create confusion in adjacent and following drivers. I am sorry, therefore, to tell you that we have concluded that your system of amber stop lamps would impair the effectiveness of the stop lamps required by Standard No. 108, and, hence is impermissible under S5.1.3.

If you have any questions you may phone Taylor Vinson of this Office (202-366-5263).

Frank Seales, Jr.
Chief Counsel