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 serial data to the front passenger door module (PDM), and body control module (BCM) to unlock their respective doors.

Schematic Reference

Door Lock/Indicator Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Power Door Latch Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

1. Ignition ON, observe the function of the door locks while performing the LOCK and UNLOCK command using a scan tool, all doors should the LOCK and UNLOCK.

⇒	If any door fails to LOCK or UNLOCK, refer to Power Door Latch System Malfunction .

2. Insert the key into the drivers door lock cylinder, turn the key clockwise for greater than 1 second and turn the key counterclockwise for greater than 1 second while observing the scan tool Door Key Cyl Unlock Switch parameters, the parameter should change between Idle and Unlock.

1. Ignition OFF, disconnect the harness connector at the driver door latch assembly.
2. Ignition ON, test for less than 10 ohms between the ground circuit terminal 8 and ground.

⇒	If greater than the specified range, test the ground circuit for an open/high resistance.

3. Verify the scan tool Door Key Cyl. Unlock Switch parameter is Idle.

⇒	If not the specified value, test the signal circuit terminal 9 for a short to ground. If the circuit tests normal, replace the DDM.

4. Install a 3A fused jumper wire between the signal circuit terminal 9 and the ground circuit terminal 8. Verify the scan tool Door Key Cyl. Unlock Switch parameter is Unlock.

⇒	If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the DDM.

5. If all circuits test normal, test or replace the driver door latch assembly.

1. Ignition OFF, disconnect the harness connector at the driver door latch assembly.
2. Test for infinite resistance between the signal terminal 9 and the ground terminal 8 with the switch in the Idle position.

⇒	If not the specified value, replace the driver door latch assembly.

3. Test for less than 2 ohms between the signal terminal 9 and the ground terminal 8 with the switch in the Unlock position.

⇒	If greater than the specified range, replace the driver door latch assembly.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.