The driver and front passenger power door lock switches are integral components of the driver door module (DDM) and passenger door module (PDM). The switches consist of 2 positions, lock and unlock, and are in the normally open state. When placed in either the lock or unlock positions, the switches provide a direct input to there respective door control module. When a power door lock switch is operated to the lock or unlock position, the associated door control module responds by sending a GMLAN serial data message indicating a change in the switch's position. This serial data message is received by the opposite door control module as well as the body control module (BCM). The DDM and PDM respond to the lock/unlock request by activating there associated power door lock motors to the appropriate direction to lock or unlock the front doors. The BCM is responsible for controlling the left and right rear passenger door lock motors. The BCM, upon receipt of a lock or unlock serial data signal, will control either the rear door lock or unlock relay. When the appropriate door lock relay is energized, the rear power door lock motors will lock or unlock the rear doors.

The power door lock motors are contained within each door latch assembly. The DDM and PDM each supply battery voltage and ground through there respective door lock and unlock actuator control circuits to its associated door latch assembly motor. The power door lock motors are reversible and are responsible for both the locking and unlocking functions of the associated door. When the door control modules receive a locking request, the modules will respond by momentarily applying voltage to the door lock actuator lock control circuit, and ground to the door lock actuator unlock control circuit. To unlock the front doors, the door control modules reverse the polarity by momentarily applying voltage to the door lock actuator unlock control circuit, and ground to the door lock actuator lock control circuit.

The left and right rear power door locks are controlled by the body control module (BCM). The BCM, upon receipt of a lock or unlock signal, will control the rear door lock or unlock relay, activating the power door lock motors in the appropriate direction to lock or unlock the rear doors. When the BCM receives a locking request, the BCM energizes the lock relay by applying voltage to the lock relay coil via the rear door lock actuator lock control circuit. With the lock relay energized, battery voltage flows through the relay controlled output circuit to both rear door lock motors causing both rear doors to lock. Ground for both rear door lock motors is supplied by the rear door unlock relay controlled output circuit. With the rear door unlock relay in a nonenergized state, the switch contacts are in a normally closed state with a path to a ground. For a rear door unlock function, the BCM energizes the unlock relay by applying ground to the unlock relay coil via the rear door lock actuator unlock control circuit. The rear door unlock relay coil is supplied with battery voltage at all times. With the unlock relay energized, battery voltage flows through the relay controlled output circuit to both rear door lock motors causing both rear doors to unlock. Ground for both rear door unlock motors is supplied by the rear door lock relay controlled output circuit. With the rear door lock relay in a nonenergized state, the switch contacts are in a normally closed state with a path to a ground.

The vehicle may be equipped with the central door unlock feature. With this feature, all doors can be unlocked from the driver door using the door key. To operate the feature, the door key is inserted into the driver door lock cylinder, turned to the unlock position and held for 3 seconds or longer, or turned to the unlock position twice within 3 seconds. The key cylinder switch contains a signal circuit and a low reference circuit. When the door key is turned to unlock, the switch contacts, which are normally open, close and the driver door module (DDM) detects a switched ground. The DDM sends a message via GMLAN serial data to the passenger door module (PDM), and body control module (BCM) to lock or unlock there respective doors.

The automatic door lock feature provides for the locking and unlocking of all the doors automatically when shifting the transmission. When the vehicle doors are closed, ignition turned ON, and the transmission is shifted out of PARK, all doors will lock. When the vehicle is stopped and the transmission is shifted into PARK, the doors will unlock.

Operation of the automatic door lock system depends upon door status information gathered by the BCM, and examined by the remote control door lock receiver (RCDLR). The system will not operate properly if the RCDLR, which is the door lock master, detects that a vehicle door is open. Each door latch contains a door open switch. Each door open switch receives voltage from the BCM and are grounded independently. When a door is open, the switch closes, voltage flows through the switch, and the BCM interprets the flow of voltage as a door open input. The BCM sends this information over the GMLAN serial data circuit where it is detected by the RCDLR. If the RCDLR determines that one of the vehicle doors is open, automatic door locking will not be permitted.

Automatic door locking is programmed during the manufacturing process, but it can be custom programmed by the operator to fit individual preferences. For information concerning custom programming available and programming instructions, refer to the vehicles owners manual.

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 body control module (BCM) senses an active state on either the left front door latch signal, secondary door latch switch signal and/or the trunk ajar switch signal circuits and the key in ignition switch signal circuit is in the YES state, the BCM, driver door module (DDM) and passenger door module (PDM) will lock the doors and then the DDM will unlock the driver door.

With any door open and a door lock switch is activated in the lock position, the driver door module (DDM), passenger door module (PDM) and the body control module (BCM) will go into a lock pending state. The BCM will also give 3 audible chimes. When the door is closed, the DDM, PDM 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.