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
    • Passenger door cylinder unlock switch
    • DRVMDL Fuse (10 amp)
    • PASS MDL Fuse (10 amp)
    • RRDR MDL Fuse (10 amp)

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

Power Door Lock Operation

The vehicle is equipped with power door locks. Each 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 passenger front door interior lock switch is wired to the passenger front door module (PDM). 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 driver door module (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 door lock operation modes are controlled by the RIM. The RIM examines the requested function from the DDM, or the remote function actuator (RFA), as well as 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 sends commands to the rest of the door modules via the power door serial data circuit to implement the selected locking function.

Power Door Lock Motors

Each door module supplies battery positive voltage and ground, through the door lock actuator motor drive 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 drive circuit the battery positive voltage is applied to, and which motor drive circuit the ground is applied to. To perform a lock function, the module applies battery positive voltage to the door lock motor Lock circuit, and ground to the door lock motor Unlock circuit. To perform a Unlock function, the module reverses the polarity and applies battery positive voltage to the door lock motor Unlock circuit, and ground to the door lock motor Lock circuit.

Front Passenger Door Power Lock Switch

In order to receive a signal from its associated door lock switch, the front passenger door module supplies battery positive voltage and ground to the switch. Their are two circuits for battery positive voltage, one for a lock signal, and one for an unlock signal. The module supplies ground to the switch via a third circuit. When the switch is activated for a lock or unlock function, voltage flows through the switch, providing the module with the neccessary signal input.

Driver Door Power Lock Switch

The driver door lock switch is the same as the 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. It also works the same way as the passenger lock switch works, but the switch signal input information is detected and processed by the DDSA. The DDSA has two circuits that supply 5 volts to 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 driver door module. When the door lock switch is activated, the voltage that flows through it is detected by the DDSA. The DDSA then relays the switch information to the driver door module via the power door serial data 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 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, either the driver door lock cylinder, or, the front passenger door lock cylinder, and turned to the Unlock position. The doors will unlock when either of the following happens:

    •  The DDM sees that its door cylinder switch is continuously closed for longer than 3 seconds.
    •  The DDM sees that its door cylinder switch is closed twice in 3 seconds.
    • The PDM sends a message over the power door serial data circuit to the DDM indicating that the passenger door cylinder switch is continuously closed for longer than 3  seconds.
    • The PDM sends a message over the power door serial data circuit to the DDM indicating that the passenger door cylinder switch has been 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 sends a power door serial data message to the other door modules to unlock all doors.

The door cylinder switches are a built in part of each doors actuator assembly and are wired to either, the driver door module (DDM) or the front passenger door module (PDM). Each door cylinder switch is connected to its exterior door key cylinder by means of a mechanical rod. Each door module supplies battery positive voltage through the door key switch signal circuit, and ground via a ground circuit to the normally open contacts of its respective switch. When the switch is closed, voltage flows through the switch, providing the door module with the neccessary signal input.

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 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 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 detects 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 doors. The DDM sends the power door serial data message to the rest of the door modules to lock the doors.

If a 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 a 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.