The Brake Transmission Shift Interlock (BTSI) is designed to prevent shifting the transaxle out of PARK without pressing the brake pedal. The BTSI solenoid is energized when the ignition switch is in the on or start position and is de-energized when the brake pedal is pressed. The stop lamp switch receives B+ when the ignition switch is in the on or start position from the BTSI fuse through circuit 1439. The stop lamp switch is normally closed, providing voltage through circuit 1135 to the BTSI solenoid, energizing the solenoid and mechanically locking the transaxle shift lever whenever it is in PARK. When the brake pedal is pressed, 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. Ground for the BTSI is supplied by circuit 434 only when the transaxle range switch is in PARK or NEUTRAL position.