The driver and passenger door lock and side window switches are integrated control module switch assemblies. The DDS and PDS door lock switches are normally open, 2 position rocker type switches, with detents for lock and unlock. The DDS and PDS are directly connected to the respective door lock actuator through the door lock actuator control circuits. When a door lock or unlock function is activated from the DDS or PDS a GMLAN lock or unlock command is sent to the other door switch and body control module (BCM). The BCM controls the rear door lock actuators through a printed circuit board relay in the IP fuse block. The unlock side of the relay is controlled by the BCM through a low side drive control circuit and the lock side of the relay is controlled through a high side drive control circuit. When the BCM grounds the door unlock control circuit, the unlock relay coil is energized and battery voltage is supplied to the unlock actuator control circuits through the unlock fuses 1 and 2. During unlock operation the actuators are grounded through the lock control circuits to the lock fuses 1 and 2 and the de-energized lock side of the relay. When the BCM supplies voltage the lock relay control circuit, the lock relay coil is energized and battery voltage is supplied to the lock actuator control circuits through the lock fuses 1 and 2. During lock operation the actuators are grounded through the unlock control circuits to the unlock fuses 1 and 2 and the de-energized unlock side of the relay.

Schematic Reference

Door Lock/Indicator Schematics

Connector End View Reference

Vehicle Access Connector End Views

Description and Operation

Power Door Locks Description and Operation

Electrical Information Reference

Scan Tool Reference

1. Verify that a test lamp connected to ground illuminates on the supply side of the unlock fuses 1 and 2 when an unlock switch is activated.

⇒	If the test lamp does not illuminate at either fuse perform the Rear Door Lock Relay Control Circuit Test.

⇒	If the test lamp does not illuminate at one fuse only perform the appropriate Actuator Circuit Test.

2. Verify that a test lamp connected to ground illuminates on the supply side of the lock fuses 1 and 2 when a lock switch is activated.

⇒	If the test lamp does not illuminate at either fuse perform the Rear Door Lock Relay Control Circuit Test.

⇒	If the test lamp does not illuminate at one fuse only perform the appropriate Actuator Circuit Test.

Rear Door Lock Relay Control Circuit Test

1. Verify that a test lamp connected to battery voltage illuminates when connected to each of the lock and unlock 1 and 2 fuses in the IP fuse block.

⇒	If the test lamp does not illuminate at all 4 fuses replace the IP fuse block.

2. Disconnect the BCM connector C7.
3. Verify that the rear door lock actuators unlock when a fused jumper wire is connected to the unlock relay control circuit terminal 9 and briefly applied to ground.

⇒	If the rear door lock actuators do not unlock test the unlock relay control circuit for an open/high resistance. If the circuit tests normal replace the IP fuse block.

4. Verify that the rear door lock actuators lock when a fused jumper wire is connected to the lock relay control circuit terminal 7 and briefly applied to battery voltage.

⇒	If the rear door lock actuators do not lock test the lock relay control circuit for an open/high resistance. If the circuit tests normal replace the IP fuse block.

5. If the circuits test normal replace the BCM.

Rear Door Lock Actuator Circuit Test

1. Verify that a test lamp connected to battery voltage illuminates when connected to each of the lock and unlock 1 and 2 fuses in the IP fuse block.

⇒	If the test lamp does not illuminate at all 4 fuses replace the IP fuse block.

2. Disconnect the affected rear door latch connector and connect a test lamp across the lock actuator control circuit terminals.
3. Verify that the test lamp illuminates briefly when a lock and unlock switch is activated.

⇒	If the test lamp does not illuminate in both switch positions test the lock actuator control circuits for an open/high resistance or short to ground. If the circuits test normal replace the IP fuse block.

4. If the circuits test normal replace the affected door latch.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.