Circuit Operation

The Brake Transmission Shift Interlock (BTSI) is designed to prevent shifting out of PARK without pressing the brake pedal. The BTSI solenoid is energized when the ignition switch is in the RUN, BULB TEST or START position and is de-energized when the brake pedal is depressed. The stop lamp switch receives ignition voltage in RUN, BULB TEST or START from the BTSI Fuse. The stop lamp switch is normally closed, providing voltage through circuit 1135 to the BTSI solenoid, energizing the solenoid and mechanically locking the transmission shift lever whenever it is in PARK. When the brake pedal is depressed, the stop lamp switch opens, removing voltage from circuit 1135 to the BTSI solenoid. This de-energizes the BTSI solenoid. allowing the vehicle to be moved out of the PARK position.

COLUMN LOCK
On the Regal with the console shift, there is a lock on the ignition key cylinder, preventing the user from removing the key while in a non-PARK position until the vehicle has returned to the PARK position.