GM Service Manual Online
For 1990-2009 cars only

Power Door Lock Components

The power door lock system consists of the following components:

    • Driver door lock switch
    • Passenger door lock switch
    • Driver door switch assembly (DDSA)
    • Driver door module (DDM)
    • Passenger door module (PDM)
    • Left rear door module (LRDM)
    • Right rear door module (RRDM)
    • Driver door lock actuator
    • Passenger door lock actuator
    • Left rear door lock actuator
    • Right rear door lock actuator
    • Driver door cylinder unlock switch
    • Class 2 serial data circuit
    • Power door serial data circuit
    • DRVMDL Fuse (10 amp)
        Driver Door Switch Assembly and Driver Door Module logic, Driver Door Module internal driver operation
    • PASS MDL Fuse (10 amp)
        Front Passenger Door Module logic and internal driver operation
    • RRDR MDL Fuse (10 amp)
        Left Rear Door Module and Right Rear Door Module logic and internal driver operation

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
    • A driver door key cylinder unlock switch activation
    • An automatic door lock function

Power Door Lock Operation

The vehicle is equipped with power door locks. Each door lock actuator is powered and controlled by the door module mounted in the individual door. The driver door module (DDM) is the master control for the door lock system but the rear integration module (RIM) determines when the lock functions are permitted.

The front passenger door interior lock switch is wired to the front passenger door module (PDM) while the driver door interior lock switch is wired to the driver door switch assembly (DDSA). Interior lock switches are not provided for the rear doors. The DDSA and the PDM send the lock switch requests to the DDM over the power door serial data circuit. The DDM then sends the lock requests to the RIM over the Class 2 serial data circuits.

The lock operation modes are controlled by the RIM. The RIM examines the lock and unlock requests from the DDM, or the remote function actuator (RFA). The RIM also examines the transmission shift selector position and the ignition switch position information available over the Class 2 serial data circuits. If the RIM determines that a lock or unlock function is permitted, it sends a class 2 message back to the DDM commanding the DDM to perform that function. The DDM then locks or unlocks the driver door and sends commands to the rest of the door modules, via the power door serial data circuit, to lock or unlock their respective doors.

Door Modules Power and Ground

In order to control power door lock operations, as well as other door functions, door modules must be powered up. Battery voltage is supplied from the rear fuse block, through separate circuits, to each door module. Each door module is separately grounded through a ground stake. The door modules also use these voltage and ground supplies to provide power and ground to the associated lock actuators, lock switches and power window switches. The rear doors, however, are not equipped with lock switches. In addition, the front door modules use these voltage and ground supplies for outside rearview mirror operations.

The DDM battery voltage circuit is fed by the DRVMDL 10 amp fuse located in the Rear Fuse Block.

The PDM battery voltage circuit is fed by the PASS MDL 10 amp fuse located in the Rear Fuse Block.

The LRDM battery voltage circuit and the RRDM battery voltage circuit are both fed by the RRDR MDL 10 amp fuse located in the Rear Fuse Block.

These circuits are in the C1 harness connector of each door module and must not be confused with the door modules voltage and ground circuits that are used exclusively to drive the power window motors.

Front Passenger Door Power Lock Switch

The front passenger door module supplies battery voltage and ground to the front passenger door lock switch. Two circuits are provided for battery voltage, one for a lock signal, and one for an unlock signal. The door module supplies ground to the switch via a third circuit. When the switch is activated for a lock or unlock function, the contacts for that function are closed to ground and voltage flows through the switch, providing the module with the neccessary lock or unlock signal input.

Driver Door Power Lock Switch

The driver door lock switch is similar to the front passenger door lock switch, but it is wired to the driver door switch assembly (DDSA), and, for a ground circuit, to the driver door module (DDM). It also works the same way as the front passenger lock switch works, but the switch signal input information is detected and processed by the DDSA and less voltage is required for operation. The DDSA has two circuits that supply 5 volts to the contacts of the driver door lock switch, one for a lock signal, and one for an unlock signal. The driver door lock switch ground circuit is provided by the DDM. When the lock switch is activated, the contacts for that function are closed to ground, the voltage flows through the switch and is detected by the DDSA. The DDSA then relays the lock switch information to the DDM via the power door serial data circuit.

Power Door Lock Motors

Each door module supplies battery voltage and ground, through the door lock actuator motor control circuits to its associated door lock actuator motor. The power door lock motors are reversible. The function performed by the lock motor, Lock or Unlock, depends on which motor control circuit the voltage is applied to, and which motor control circuit the ground is applied to. To perform a lock function, the door module applies voltage to the door lock motor Lock circuit, and ground to the door lock motor Unlock circuit. To perform an Unlock function, the door module reverses the polarity, applying voltage to the door lock motor Unlock circuit, and ground to the door lock motor Lock circuit.

Automatic Door Locks

The automatic door lock system provides for locking or unlocking all or one of the doors when shifting the transmission in and out of PARK, or, when turning the ignition key to the OFF position. This system is commanded according to the information stored in the rear integration module (RIM). The RIM receives the features selected by the driver from the driver information center (DIC). The RIM commands the driver door module (DDM) which in turn commands the individual passenger door modules. For customized selections available and programming instructions, refer to: Personalization Description and Operation in Personalization.

Anti-Lockout Feature

Leaving the key in the ignition with any door open will disable the use of the power door locks and the Remote Keyless Entry (RKE) lock function.

The anti-lockout feature can be overridden by holding the lock switch in the LOCK position for more than 3 seconds.

Central Door Unlock

The central door unlock feature is activated when the driver door key is inserted into the driver door lock cylinder and turned to the Unlock position. The driver door lock cylinder is connected, by means of a mechanical rod, to the driver door key switch, which is a built in part of the driver door lock actuator assembly. The driver door module (DDM) supplies battery positive voltage through the door key switch signal circuit, and ground via a ground circuit to the normally open contacts of the driver door key switch. When the driver door lock cylinder is turned to the unlock position the switch contacts are closed and voltage flows through the switch. This provides the DDM with the appropriate signal input. The doors will unlock when either of the following happens:

    •  The DDM senses that the door cylinder switch is continuously closed for longer than 3 seconds.
    •  The DDM senses that the door cylinder switch is closed twice in 3 seconds.

The DDM sends a Class 2 message to the RIM indicating the above. The RIM sends a Class 2 message to the DDM to unlock all doors. The DDM unlocks the driver door and sends a power door serial data message to the passenger door modules to unlock their respective doors.

Delayed Locking Feature

This personalization feature permits the delay of all door locking until 5 seconds after the last door is closed. This feature is controlled by the rear integration module (RIM), which operates based on data received over the Class 2 serial data circuits.

  1. When the lock function is requested, either by the remote function actuator (RFA) or the driver door module (DDM), while the drivers door is open and the ignition key is removed from the ignition, the RIM commands the radio, via the Class 2 serial data circuit, to sound the chime 3 times to signal that the delayed locking is active.
  2. When the DDM determines that the driver door is closed, and receives the message from the other door modules that their respective doors are also closed, it sends a Class 2 message to the RIM.
  3. The RIM waits for 5 seconds, then sends the Class 2 message to the DDM to lock the doors. The DDM locks the driver door and sends the power door serial data message to the passenger door modules to lock their respective doors.

If any door is opened during the 5 second delay period, the RIM resets the timer and waits until it again receives the doors closed message from the DDM to restart the delay period.

Pressing a power lock switch on any door or on the remote transmitter for the RFA causes the RIM to override this feature and lock all doors immediately.

To program the delayed locking feature, refer to Personalization Description and Operation in Personalization.