GM Service Manual Online
For 1990-2009 cars only

Door Lock System Components

The power door lock system consists of the following components:

    • Driver door lock switch
    • Front passenger door lock switch
    • Door lock relay
    • Remote control door lock receiver - w/keyless entry
    • Door lock actuators in each of the doors
    • POWER ACCESSORIES 30A fuse

Door Lock System Controls

The power door lock system can be controlled by any of the following:

    • A power door lock or unlock switch activation
    • A keyless entry lock or unlock transmission

Driver and Passenger Door Lock Operation - without Keyless Entry

When any of the door lock switches are placed in the lock position, voltage is applied to the door lock relay control circuit and the lock relay winding. Since the other side of the lock relay winding is connected to ground, the relay is energized. This causes the contacts to close and complete the path from the POWER ACCESSORIES fuse through the battery voltage circuit. Voltage is then applied to the door lock actuator lock circuit to the lock side of the door lock actuators. Since the other side of the all the door lock actuators are connected through the door lock actuator unlock circuit to the normally closed contacts of the unlock relay to ground, the doors lock.

Driver and Passenger Door Lock Operation - with Keyless Entry

On vehicles equipped with keyless entry, the passenger door lock actuators lock in the same manner as described above, however, the driver door lock actuator has the driver door lock actuator unlock circuit connected to the remote control door lock receiver. The remote control door lock receiver internally grounds the driver door lock actuator.

Driver and Passenger Door Unlock Operation - without Keyless Entry

When any of the door lock switches are placed in the unlock position, voltage is applied to the door unlock relay control circuit and the unlock relay winding. Since the other side of the unlock relay winding is connected to ground, the relay is energized. This causes the contacts to close and complete the path from the POWER ACCESSORIES fuse through the battery voltage circuit. Voltage is then applied to the door lock actuator unlock circuit to the unlock side of the door lock actuators. Since the other side of the door lock actuators are connected through the door lock actuator lock circuit to the normally closed contacts of the lock relay to ground, the doors unlock.

Driver and Passenger Door Unlock Operation - with Keyless Entry

On vehicles equipped with keyless entry, the passenger door lock actuators unlock in the same manner as described above, however, the driver door lock actuator has the door lock actuator unlock circuit connected to the remote control door lock receiver. The remote control door lock receiver monitors the door unlock relay control circuit and when it senses an unlock switch activation it internally switches the driver door lock actuator unlock control circuit to battery voltage. This is done so that the driver door can be unlocked separately using the keyless entry transmitter.