The power door lock sub-system is comprised of the following components:

The remote function actuator (RFA) module is the door lock master device. The RFA has final control over whether or not all of the doors will lock or unlock under power. The RFA will not allow any doors to be power locked unless the key is out of the ignition and the doors are all closed as indicated by the door jamb switches.

The driver's door module (DDM) directly controls the driver's door lock actuator motor. The DDM receives and forwards the driver's door switch lock request messages to the remote function actuator (RFA) via the serial data link. The RFA receives the request message and examines the message for lockout prevention criteria. If the conditions are proper, the RFA sends a lock or an unlock command message back to the DDM. The DDM forwards door lock messages received from the RFA to the passenger door module (PDM) and the rear door module (RDM) over a simple bus interface (SBI) line. The DDM also contains a class 2 serial interface which communicates with other vehicle system modules. The left front door power window and the outside power mirror are also controlled through the DDM. Battery voltage is always applied to the DDM through the retained accessory power (RAP) circuit breaker located in the underhood Maxifuse® block.

The passenger's door module (PDM) controls the passenger's door lock actuator. The PDM also monitors the passenger's power door lock switch. The right front door power window and the outside power mirror are also controlled through the PDM.

The rear door module (RDM) controls both of the rear door lock actuators. The RFA commands the driver door module (DDM) to lock or unlock the doors via a class 2 serial data message. The DDM then forwards this command to the RDM in the form of a simple bus interface serial data message.

The power door lock switch is a multiplexed switch device that communicates with the driver's door module (DDM) via the simple bus interface (SBI) serial data link. The left front power door lock switch feeds the left front power window switch, which then transmits a switch activity message to the DDM.

The right front power door lock switch directly switches the passenger door module (PDM) input. The PDM then transmits a switch activity message to the driver door module (DDM) over the simple bus interface (SBI).

The power door lock actuators receive their power from the door modules. The door modules apply battery voltage of the correct polarity to their respective door lock motors when any door lock switch is operated, driving the door lock lever in or out. The rear doors have no power lock buttons, only manual lock levers. The power door lock switches are generally closed for just a moment. If the power door lock switches are held closed for too long, an electronic circuit breaker in each actuator will open in order to protect the motor against damage. The circuit breakers have positive temperature coefficients (PTC) and will reset automatically when voltage is removed from the actuator. When either the left or the right front power door lock switch is activated, all of the doors are locked or unlocked in unison. Each door lock actuator assembly contains a manual door lock lever. The lock levers move with actuator position and may be used in order to independently lock or unlock any individual door at any time. Both front doors have key cylinders that will unlock and lock the doors and move the lock actuators. When the driver's door key cylinder is turned, all of the doors will unlock. The key locks and the manual lock levers will still work if electrical power is lost.

The class 2 and simple bus interface (SBI) are both serial data links. The serial data links replace the cables in the vehicle by multiplexing (time-sharing) data to and from each device over a single wire referenced to ground. If the SBI is lost, both the rear door module (RDM) and the passenger door module (PDM) enter the sleep mode. With the RDM and the PDM in sleep mode, no power door lock operations are possible.

When the passenger power door lock switch is pressed, the following events occur:

1. The passenger door module (PDM) will directly sense actuation of the passenger door power lock switch.
2. The PDM will send a serial data link message to the driver's door module (DDM) requesting that the doors be locked.
3. The DDM receives and forwards the lock request message to the remote function actuator (RFA) via a serial data link.
4. The RFA receives the request message and examines for the following lockout prevention criteria:

•	IGNITION SWITCH KEY PRESENT signal (CKT 80) from the ignition switch

•	DRIVER DOOR OPEN message from the DDM

•	Last door closed locking (LDCL) function active message from the instrument panel cluster (IPC)

5. The RFA broadcasts a serial data link command message in order to lock all of the doors when the following conditions exist:

•	The ignition key is out of the ignition switch and the LDCL is inactive, as soon as the driver's door is closed.

•	The LDCL is active as soon as all of the doors are closed for 5 seconds.

•	The driver's power door lock switch is held in the LOCK position for greater than 3 seconds (lockout override).

6. The DDM receives and transmits the command message from the RFA to the PDM and the rear door module (RDM).
7. All 3 modules actuate their door lock motors, thus completing the locking sequence.

The last door closing locking (LDCL) feature provides a wait state following a lock switch or a keyless entry transmitter LOCK command. When a lock command is received, the key must be out of the ignition switch and all of the doorjamb switches must indicate closed before any of the doors are locked. Once all of the doors close, a 5 second delay is provided for re-entry prior to locking the doors.

The LDCL feature may be activated by the customer through pressing the power door lock switch and then pressing a valid keyless entry transmitter UNLOCK button. Repeating this sequence will toggle the LDCL off and on. LDCL mode active is the standard setting for both keyless entry transmitters as delivered to the dealer.

The automatic door lock (ADL) function provides for locking or unlocking the doors when shifting the transmission in and out of PARK. Customized selections may be made as follows:

1. No automatic door lock or unlock
2. Automatic all door lock when shifter moves out of PARK.

No automatic door unlock

3. Automatic all door lock when shifter moves out of PARK.

Automatic driver door unlock when shifter moves into PARK.

4. Automatic all door lock when shifter moves out of PARK.

Automatic all door unlock when shifter moves into PARK.

The driver's door module (DDM) communicates with the remote function actuator (RFA) module over the class 2 data link. The RFA module receives powertrain control module (PCM) shift select changes. Whenever the left front door is closed, the ignition is in the RUN position, and the gear selector is shifted out of PARK, the RFA module will transmit a class 2 lock doors message to the DDM. The DDM will send this message on to the other door modules over the simple bus interface (SBI) and the modules will lock their doors as programmed. If personalization is selected to do so, the RFA will also unlock the doors when the gear selector lever is put back in to the PARK position. Refer to Keyless Entry System Operation in Keyless Entry.