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
    • Passenger door lock switch
    • Door lock relay - w/keyless entry
    • Remote control door lock receiver - w/keyless entry
    • Door lock actuators in each of the doors
    • PWR ACCY 25A circuit breaker
    • CIG LTR 20A fuse - w/keyless entry

Door Lock System Controls

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

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

Door Lock System Operation - without Keyless Entry

Voltage is available to both the driver and passenger door lock switches at all times from the PWR -- ACCY circuit breaker through the battery positive voltage circuit. The normally closed contacts of both door lock switches are wired in series through the door lock and unlock control circuits directly to ground, available at the driver door lock switch. The door lock actuators are wired in parallel through the door lock actuator lock and unlock control circuits which are connected to the normally closed contacts of the passenger door lock switch.

By placing the driver door lock switch in the lock position, voltage is applied through the door lock control circuit to the normally closed lock switch contact of the passenger door lock switch. Voltage is then applied to the lock side of the door lock actuators through the door lock actuator lock circuit. Since the unlock side of the door lock actuators are connected to ground through the normally closed unlock switch contacts of the passenger and driver door lock switches, the doors lock. By placing the driver door lock switch in the unlock position, the polarity is reversed and the doors unlock.

Door Lock Operation - with Keyless Entry

Vehicles equipped with keyless entry incorporate a remote control door lock receiver and a door lock relay in the door lock system. This is done to gain remote access to the door lock system. This system isolates the driver door so that it may be unlocked individually and can also control interior illumination and the horn system. For further information, refer to Keyless Entry System Description and Operation in Keyless Entry.

Voltage is available to both the driver and passenger door lock switches at all times from the CIG LTR fuse through the battery positive voltage circuit . When any of the door lock switches are placed in the lock position, voltage is applied to the door lock 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 PWR ACCY circuit breaker 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 passenger door lock actuator is connected through the door lock actuator unlock circuit to the normally closed contacts of the unlock relay to ground, and driver door is connected through the door lock motor unlock circuit to the remote control door lock receiver to ground, the doors lock.

When any of the door lock switches are placed in the unlock position, voltage is supplied through the door lock control circuit to the lock relay winding and also to the remote control door lock receiver. 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 PWR ACCY circuit breaker through the battery voltage circuit. Voltage is then applied to the door lock actuator unlock circuit to the unlock side of the passenger door lock actuator. The remote control, door lock receiver, upon receiving the unlock signal will supply voltage to the unlock side of the driver door lock actuator through the driver door lock actuator unlock circuit. Since the other side of the driver and passenger 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.