Robert C. Lange, Executive Director
    Vehicle Structure and Safety Integration
    GMNA Product Development
    General Motors Corporation
    30200 Mound Road
    Warren, MI 48092-2025

    Dear Mr. Lange:

    This responds to your request asking whether a GM driver and passenger seat belt reminder system recently developed by General Motors Corporation (GM) violates any Federal motor vehicle safety standards. The GM system, as described, is not prohibited by any such standards.

    According to your letter, the GM system consists of a multi-stage chime and lamp warning cycle that lasts 75 seconds and is repeated three times per ignition cycle. Buckling the driver or passenger seat belt at any time will stop all warning systems for that seating position. Each cycle consists of three phases. The first phase lasts 8 seconds and consists of both a chime and a seat belt warning lamp. The next, 12-second phase consists of a seat belt warning lamp without a chime. The third phase lasts 55 seconds and consists of a flashing seat belt warning lamp. The first cycle begins when the ignition is turned on. The second cycle follows 30 seconds after the first cycle is completed, and the third stage follows 180 seconds after the second cycle is completed.

    The only safety standard that could conceivably prohibit the GM system is Federal motor vehicle safety standard No. 208, Occupant crash protection (FMVSS No. 208). S7.3 of that standard requires the driver's seating position be equipped with a seat belt warning system that activates, under specified circumstances, a continuous or intermittent audible signal for a period of "not less than 4 seconds and not more than 8 seconds," and a continuous or flashing warning light for not less than 60 seconds after the ignition switch is turned on. The 75-second cycle described in your letter meets both of these criteria. Thus, the only remaining question is whether the two additional cycles are permitted under the standard.

    The prohibition on any audible signal lasting longer than 8 seconds reflects a statutory requirement imposed by Congress in response to public resistance to seat belt interlock systems.[1] 49 U.S.C. 30124 provides, in relevant part, that a motor vehicle safety standard "may not require or allow a manufacturer to comply with the standard by...using...a buzzer designed to indicate a safety belt is not in use, except a buzzer that operates only during the 8-second period after the ignition is turned to the 'start' or 'on' position."

    While the statute prohibits the National Highway Traffic Safety Administration from requiring, or specifying as a compliance option, an audible seatbelt warning that sounds outside of the specified 8-second period, it does not prohibit vehicle manufacturers from placing such systems in their vehicles. However, given FMVSS No. 208's requirement that the required seat belt warning be no longer than 8 seconds, a vehicle manufacturer wishing to provide a voluntary audible signal must provide some means of differentiating the voluntarily provided signal from the required signal. One way to differentiate between the two signals is a clearly distinguishable lapse in time between the two signals. The GM system, as described, provides a 97-second interval between the first and second audible signals and a 247-second interval between the second and third audible signals. These time lapses are sufficiently long to make the second and third audible signals clearly distinguishable from the initial, required 8-second signal. Accordingly, the two additional cycles are permitted under the standard.

    I hope this information addresses your concerns. If you have any further questions, please feel free to contact Rebecca MacPherson of my staff at (202) 366-2992.


    Jacqueline Glassman
    Chief Counsel


    [1] See House report 93-1452, pp. 44-45.