GM Service Manual Online
For 1990-2009 cars only

Automatic Transmission Shift Lock Control Description for Chevrolet Monte Carlo 1999

The Brake Transaxle Shift Interlock (BTSI) system prevents the driver from shifting out of PARK without simultaneously pressing the brake pedal. The energized BTSI solenoid locks the automatic transaxle control lever.

The de-energized BTSI solenoid releases the automatic transaxle control lever when pressure is applied to the brake pedal. Refer to Restraints.