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 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 their respective 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

Programming and Relearning (Programming and Relearning) for scan tool information


Circuit/System Verification

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

• If any door fails to LOCK or UNLOCK, refer to Power Door Locks Inoperative (Power Door Locks Inoperative) .

2. Observe the scan tool Key Cyl Unlock Switch parameters while the turning and holding the key in the driver door lock cylinder to the left and then to the right, parameter should change from Idle to Unlock.



Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the driver door lock switch.
2. Ignition OFF, scan tool OFF, test for less than 10.0 ohms between the low reference circuit terminal B and ground.

• If greater than the specified range, test the low reference circuit for an open/high resistance.

3. Ignition ON, verify the scan tool Door Key Cyl. Unlock Switch parameter is Idle.

• If not the specified parameter, test the signal circuit terminal A 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 A and the low reference circuit terminal B. Verify the scan tool Door Key Cyl. Unlock Switch parameter is Unlock.

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

5. If the circuits test normal, test or replace the driver door lock switch.



Component Testing

1. Ignition OFF, disconnect the harness connector at the driver door lock key cylinder switch.
2. Test for infinite resistance between the signal terminal A and the low reference terminal B with the switch in the Idle position.

• If not the specified value, replace the driver door lock key cylinder switch.

3. Test for less than 2.0 ohms between the signal terminal A and the low reference terminal B with the switch in the Unlock position.

• If greater than the specified range, replace the driver door lock key cylinder switch.




Repair Instructions

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

* Door Lock Cylinder Replacement (Service and Repair)
* Programming and Relearning (Programming and Relearning) for DDM replacement, setup, and programming