For 1990-2009 cars

### 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
--- | --- | --- | --- | ---
Driver Door Key Switch Signal | 1 | 1 | 1 | --
Low Reference (AXC/AXE) | -- | 1 | -- | --
Ground (Except AXC/AXE) | -- | 1 | -- | --
1. Key Cylinder Switch Inoperative

### Circuit/System Description

#### Except RPO AXC/AXE

The key cylinder unlock feature will unlock all of the doors when the body control module (BCM) receives a Key Unlock Switch signal for greater than 1 second and will unlock all of the doors.

#### RPO AXC/AXE

The key cylinder unlock feature will unlock all of the doors when the driver door module (DDM) receives a Key Unlock Switch signal for greater than 1 second and will send a request to the passenger door module (PDM) and the BCM to unlock all of the doors.

### Reference Information

#### Schematic Reference

Door Lock/Indicator Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

Power Door Locks 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

Ignition OFF, insert the key into the drivers door lock cylinder, turn the key clockwise and hold for greater than 1 second and turn the key counterclockwise and hold for greater than 1 second while observing the scan tool Door Key Cyl Unlock Switch parameter. The reading should change between Active and Inactive (except AXC/AXE) or idle and unlock (AXC/AXE).

### Circuit/System Testing

#### Except RPO AXC/AXE

1. Ignition OFF, disconnect the harness connector at the driver door latch assembly.
2. Test for less than 1.0 ohm 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 Key Cyl Unlock Switch parameter is Inactive.

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

4. Install a 3-amp fused jumper wire between the signal circuit terminal 9 and ground, verify the scan tool Door Key Cyl Unlock Switch parameter is Active.

⇒ | 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 BCM.

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

#### RPO AXC/AXE

1. Ignition OFF, disconnect the harness connector at the driver door latch assembly.
2. Ignition ON, 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.

3. Install a 3-amp fused jumper wire between the signal circuit terminal 9 and ground, verify the scan tool Door Key Cyl Unlock Switch parameter is Unlock.

⇒ | If not the specified value, test the signal circuit for an open/high resistance. If the circuit tests normal, replace the DDM.

4. Install a 3-amp fused jumper wire between the signal circuit terminal 9 and the low reference circuit terminal 8, verify the scan tool Door Key Cyl Unlock Switch parameter is Unlock.

⇒ | If not the specified value, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the DDM.

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

### Component Testing

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 open position.

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

3. Test for less than 2.0 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.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Door Lock Cylinder Replacement

• | Front Side Door Latch Replacement

• | Control Module References for BCM and DDM replacement, setup and programming