For 1990-2009 cars

The brake transmission shift interlock (BTSI) is designed in order to prevent shifting the transaxle out of PARK without pressing the brake pedal. The BTSI solenoid is energized when the ignition switch is in ON or START. The BTSI solenoid is de-energized when the brake pedal is pressed. The brake switch C2 receives ignition voltage in ON or START from the NSBU fuse through CKT 275. The brake switch is normally closed, providing voltage through CKT 1135 to the BTSI solenoid. This energizes the solenoid and mechanically locks the transaxle shift lever whenever the shift lever is in PARK. When the brake pedal is pressed, the brake switch opens. This removes voltage from CKT 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 solenoid is supplied by CKT 250.