GM Service Manual Online
For 1990-2009 cars only

Description

The brake transaxle shift interlock (BTSI) system is comprised of the following components:

    • The shift interlock actuator within the steering column (or under the console)
        The actuator is used in order to lock the gear shift lever.
    • The brake-pedal mounted stoplamp/BTSI switch
        This switch is used in order to enable/disable the shift interlock actuator.
    • The control circuitry
        The circuitry establishes the conditions for operation of the BTSI system.

Operation

The brake transaxle shift interlock (BTSI) is a safety circuit that prevents the vehicle from accidently shifting out of PARK when the ignition switch is in RUN. The vehicle is equipped with a shift interlock actuator. This actuator, when energized, physically blocks the gear shift lever from moving out of PARK when the ignition switch is in RUN. The shift actuator de-energizes, allowing the gear shift lever to move, by pressing the brake pedal.