Interpretation ID: nht90-4.21

TYPE: Interpretation-NHTSA

DATE: September 26, 1990

FROM: Paul Jackson Rice -- Chief Counsel, NHTSA

TO: James R. Mitzenberg -- Project Engineer, The Flxible Corporation

TITLE: None

ATTACHMT: Attached to letter dated 1-25-90 from J.R. Mitzenberg to S.P. Wood (OCC 4371)

TEXT:

This is in reply to your letter requesting an interpretation of Federal Motor Vehicle Safety Standard No. 108.

Your company offers an optional transmission retarder for supplemental braking. It is electrically operated during the initial travel of the service brake pedal. As the service brake pedal is further depressed, air is emitted from the brake valve and t he service brakes are activated. You have asked whether a noncompliance with S4.5.4 would result. This section (now renumbered S5.5.4) states that the stop lamps shall be activated upon application of the service brakes. You point out that if the stop lamps are activated by the retarder, the stop lamps could be illuminated without the service brakes actually being applied during the initial travel of the service brake pedal, and up until the point in time that air is actually emitted from the brake p edal and into the service brake system.

In our opinion there is no failure to comply by the system as you have described it. We view application of the brake pedal as evidencing an intent to slow or stop the vehicle. Thus, the operation of the stop lamp is a consequence of the application of the brake pedal.

We appreciate your interest in enhancing safety with the added benefits that the retarder provides in early activation of the stop lamp.