GM Service Manual Online
For 1990-2009 cars only

The brake transmission shift interlock (BTSI) system prevents the automatic transmission from being shifted out of PARK unless the brake pedal is depressed. When the brake pedal is depressed, the BTSI solenoid releases a lock pawl. This enables the shift linkage to move and the shift lever to operate.

When service operations are required, the BTSI system can be overridden.

On vehicles equipped with a column-mounted shift lever, override the BTSI system by performing the following steps:

  1. Turn the ignition switch to the OFF position.
  2. Remove battery voltage from the solenoid.
  3. Turn the ignition switch to the ON position.

For vehicles equipped with floor-mounted shift levers, an override lever is mounted on the right side of the assembly. The override lever can be accessed by removing the shift lever boot. Push the lever to the left in order to override the BTSI.

For more information refer to Automatic Transmission Shift Lock Control Circuit Description .