GM Service Manual Online
For 1990-2009 cars only

The operation of the power door lock switch locks and unlocks all of the doors. Manual operation of each lock is also possible. Reversible motors that receive voltage from the PWR ACCY circuit breaker operate the locks. The power door lock switches operate in order to turn the motors on by supplying battery voltage to one of the terminals and by grounding the other terminal.

Moving the power door lock switch to the LOCK position completes the circuit to the motors. Voltage is available to CKT 295 (GRY) and to the door lock motors. The door lock motors ground through CKT 294 (TAN), through the other switch contract, through the door lock relay to CKT 150 (BLK), and ground G200. The motor in each door runs in order to operate the power door locks. Release of the door lock switch opens the circuit, and the motors cease.

A similar action occurs with either of the power door switches closing to the UNLOCK position. CKT 294 (TAN) to the motors supplies battery voltage. CKT 295 (GRY) provides ground. The polarity of the voltage to the motors reverses. The motors run in the opposite direction in order to unlock the doors.

The power door lock switches usually close for just a moment. If you hold the power door lock switches closed, a circuit breaker in each motor opens in order to protect against damage. The circuit breakers close automatically when the circuit breakers cool.

Rear Cargo Doors

The power door lock motor does not operate unless the rear cargo doors are fully closed. The power door lock motor is in the right cargo door. The contactors are on the rear cargo door opening on the body and on the right cargo door.