The brake transmission shift interlock (BTSI) system prevents the 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, enabling the shift cable to move and the shift lever to operate.

The BTSI system can be overridden to perform service operations. Do this by turning the ignition switch to ON, in order to remove the battery voltage from the solenoid and override the BTSI.