GM Service Manual Online
For 1990-2009 cars only

Power Door Locks System Components

The power window system consists of the following components:

    • Body control module (BCM)
    • Driver door lock cylinder switch
    • Front passenger door lock cylinder switch
    • Driver door lock switch
    • Front passenger door lock switch
    • Door lock actuators in each of the doors
    • DR LK Fuse 20-amp

Door Lock System Controls

The Power Door Lock System is controlled by the body control module (BCM) and can be activated by any one of the following:

    • A door lock switch lock or unlock actuation
    • A door lock cylinder switch unlock actuation
    • A keyless entry transmitter actuation
    • An automatic door lock actuation (Personalization function)
    • An automatic door unlock actuation (Personalization function)

Door Lock Operation

When the body control module (BCM) detects a transition of either of the door lock switches to the lock position, it switches the door lock actuator lock control circuit to voltage. Since the lock actuator unlock control circuits are at ground potential within the BCM, the door lock actuator motors transition to the lock position.

Driver Door Unlock Operation

When the body control module (BCM) detects a transition of either of the door lock switches to the unlock position, it switches the driver door lock actuator unlock control circuit to voltage. Since the door lock actuator lock control circuit is at ground potential within the BCM, the left front (LF) door lock actuator motor transitions to the Unlock position.

The driver door lock actuator unlock control circuit is a dedicated control circuit used only for the driver door lock actuator motor. This is done so that the driver door may be unlocked by itself using a keyless entry transmitter or an automatic door unlock function (if programmed).

Passenger Door Unlock Operation

When the body control module (BCM) detects a transition of either of the door lock switches to the unlock position, it switches the door lock actuator unlock control circuits to voltage. Since the door lock actuator lock control circuit is at ground potential within the BCM, the passenger door lock actuator motors transition to the unlock position.

The door lock actuator unlock control circuits are dedicated control circuits used only for the passenger door lock actuator motors. This is done so that the driver door may be unlocked separate from the passenger doors using a keyless entry transmitter or an automatic door unlock function (if programmed).

Lockout Prevention

This function is intended to prevent the vehicle operator from locking the doors if the key is left in the ignition and any vehicle door is open. The body control module (BCM) will react after locking all the doors by unlocking the driver door. The lockout prevention function can be overridden by manually locking the door.

Key Cylinder Unlock

The body control module (BCM) will provide unlocking of all the doors when either the driver or front passenger key cylinder switch is actuated to the unlock position for longer than one second.

Automatic Door Lock/Unlock

The automatic door lock/unlock function is a Vehicle Personalization feature with the following four programmable modes of operation:

  1. The automatic door lock feature is disabled.
  2. All of the doors lock when the vehicle is shifted out of Park with the ignition ON.
  3. All of the doors lock when the vehicle is shifted out of Park with the ignition ON, and only the driver door Unlocks when the vehicle is shifted into Park.
  4. All of the doors lock when the vehicle is shifted out of Park with the ignition ON, and all of the doors Unlock when the vehicle is shifted into Park.

The automatic door lock function can only be enabled by the body control module (BCM) if the driver door open switch and door ajar switches are in the Closed state. For information on programming the automatic door locks, refer to Vehicle Personalization .

Air Bag Deployment Unlock

The body control module (BCM) will provide unlocking of all the doors 15 seconds after determining the air bags have been deployed.