GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2009 🢒 SRX 🢒 Body Systems 🢒 Vehicle Access 🢒 Power Door Lock Key Cylinder Switches Inoperative

Diagnostic Instructions
    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    •  Diagnostic Procedure Instructions provides an overview of each diagnostic category.

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Door Lock Key Switch Signal

1

1

1

--

Driver Door Latch Ground

--

1

1

--

1. Key Cylinder Switch Malfunction

Circuit/System Description

The driver door latch contains a signal circuit and a ground 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 passenger door module (PDM), and body control module (BCM) to lock or unlock their respective doors.

Reference Information

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

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification
  1. Ignition ON, command the doors to LOCK and UNLOCK by using the driver door lock switch, all doors should perform the LOCK and UNLOCK functions.
    2. ⇒If any door fails to LOCK or UNLOCK, refer to Power Door Latch System Malfunction .
  2. Insert the key into the driver door lock cylinder, turn the key to the UNLOCK position while observing the scan tool Door Key Cyl. Unlock Switch parameter, the parameter should change from Idle to Unlock.

Circuit/System Testing
  1. Ignition OFF, disconnect the harness connector at the driver door latch.
  2. Test for less than 10 ohms between the ground circuit terminal 8 and ground.
    3. ⇒If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Ignition ON, verify the scan tool Door Key Cyl. Unlock Switch parameter is Idle.
    4. ⇒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.
    5. ⇒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 the circuits test normal, test or replace the driver door latch.

Component Testing
  1. Ignition OFF, disconnect the harness connector at the driver door latch.
  2. Test for infinite resistance between the signal terminal 9 and the ground terminal 8 with the switch in the Idle position.
    3. ⇒If not the specified value, replace the driver door latch.
  3. Test for less than 2 ohms between the signal terminal 9 and the ground terminal 8 with the switch in the Unlock position.
    4. ⇒If greater than the specified range, replace the driver door latch.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Front Side Door Latch Replacement
    •  Control Module References for DDM replacement, setup, and programming