GM Service Manual Online
For 1990-2009 cars only

Power Door Lock Components

The power door lock system consists of the following components:

    • The driver door module (DDM)
    • The front passenger door module (FPDM)
    • The body control module (BCM)
    • The rear door lock relay
    • The rear door unlock relay
    • The door lock actuators in each of the doors

Door Lock System Controls

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

    • A power door lock switch activation
    • A keyless entry transmission
    • An automatic door lock function
    • A delay lock function
    • Door lock cylinder switch activation
    • Lockout Prevention

Power Door Lock System Operation

The front power door lock switches are integral components of the driver door module (DDM) and front passenger door module (FPDM). The switches are 2 position normally open rocker switches. When placed in either the lock or unlock positions, the switches provide a direct input to the DDM or FPDM. The DDM or FPDM monitors these inputs and sends a GMLAN message indicating a change in the switch's respective position. Modules which activate the power door lock actuators receive the lock or unlock message and activate the actuator in the appropriate direction to lock or unlock the vehicle's doors.

The modules which activate the power lock motors are:

    • The DDM (driver door lock actuator)
    • The FPDM (passenger front door lock actuator)
    • The BCM (both rear door lock actuators)

The DDM and FPDM are directly connected to the respective door lock actuator through the lock and unlock control circuits. Once a door lock or unlock request has been received, the module will supply battery voltage to one side of the actuator and ground the other causing the doors to lock or unlock

The rear passenger doors are controlled by the BCM through the rear door lock and unlock relays which are located in the rear fuse block. The BCM controls the unlock relay by providing ground to energize the coil and controls the lock relay by providing battery voltage to energize the relay coil. The energized the relay and allows voltage to be applied to either the door lock motor lock or unlock circuits. Since the other side of the door lock actuator is connected to the normally closed contacts of the opposing relay to ground, the doors lock or unlock.

Programmable Automatic Door Locks

The automatic door lock feature can be programmed to control the door lock system. The automatic door lock feature is factory programmed to have all doors lock and unlock.

When the automatic door lock feature is programmed to control the door lock system, the DDM, FPDM and BCM will lock the vehicle doors if the following inputs are true:

    • Ignition 1 input is active.
    • All door ajar switch inputs are inactive.
    • Transaxle is shifted out of PARK.

This automatic door lock function will only occur once per ignition cycle unless, a door ajar switch input changes state to active and back to inactive. Then the DDM, FPDM and BCM will lock all doors again.

Once the automatic door lock feature has locked the doors, the BCM will then unlock all the doors when the transaxle is shifted into PARK.

Lockout Prevention

This feature prevents the locking of the driver door if the ignition key is left in the ignition lock cylinder. If a lock function occurs from any door lock switch and the BCM senses an active state on either the left front door latch signal, secondary door latch switch signal and the key in ignition switch signal circuit is in the YES state, the BCM, DDM and FPDM will lock the doors and then the DDM will unlock the driver door.

Delayed Locking Operation

With any door open and a door lock switch is activated in the lock position, the DDM, FPDM and the BCM will go into a lock pending state. The BCM will also give 3 audible chimes. When the door is closed, the DDM, FPDM and the BCM will lock the doors after approximately 5 seconds. This feature can be overridden by activating the door lock switch a second time and the doors will lock even with a door open.