Power Door Lock Key Cylinder Switches Inoperative

Power Door Lock Key Cylinder Switches Inoperative

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) provides an overview of each diagnostic category.



Diagnostic Fault Information






Circuit/System Description

The driver door key switch is contained within the driver door latch assembly. The driver door key cylinder switch contacts, which are normally open, receive a constant ground via the G200 ground circuit. When the door key is turned to unlock, the switch contacts close and the driver door module (DDM) detects a switched ground. The DDM sends a message via GMLAN serial data to the remote control door lock receiver (RCDLR), indicating the key cylinder unlock switch request. The RCDLR is the master of all lock and unlock operations. If the RCDLR determines that the key cylinder unlock switch request is valid and conditions are correct for the door modules to perform the unlock function, it sends a message via GMLAN serial data back to all door modules to unlock all doors.


Reference Information
Schematic Reference

Door Lock/Indicator Schematics (Door Lock/Indicator Schematics)
Connector End View Reference

Component Connector End Views (Connector Views)
Description and Operation

Power Door Locks Description and Operation (Description and Operation)
Electrical Information Reference

* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)

Scan Tool Reference

Control Module References (Programming and Relearning)


Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the driver door latch assembly.
2. Ignition OFF, scan tool OFF, test for less than 10.0 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. Ignition ON, verify the scan tool door cylinder 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 cylinder unlock switch parameter changes to either UNLOCK or LOCK.

• If not one of the specified values, 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.



Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

* Front Side Door Lock Replacement (Front Side Door Lock Replacement)
* Control Module References (Programming and Relearning) for DDM replacement, setup, and programming