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.

### DTC Descriptors

DTC B3125 00: Left Front/Driver Door Only, Unlock Circuit
DTC B3130 00: All Unlock Circuit
DTC B3135 00: All Door Lock Circuit

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
I/P Fuse Block B+ | 1, 2, 3 | 1, 2, 3 | -- | --
Left Lock Switch Signal | B3150 00 | B3150 00 | B3150 00 | --
Left Unlock Switch Signal | B3140 00 | B3140 00 | B3140 00 | --
Right Lock Switch Signal | B3155 00 | B3155 00 | B3155 00 | --
Right Unlock Switch Signal | B3145 00 | B3145 00 | B3145 00 | --
Door Latch Control | 1, 2, 3 | 1, 2, 3 | 1, 2, 3 | --
Doors Unlock Control | B3130 00 | B3130 00 | B3130 00 | --
LF Door Unlock Control | B3125 00 | B3125 00 | B3125 00 | --
Doors Locked Control | B3135 00 | B3135 00 | -- | --
Door Lock Switch Ground | -- | 1, 2, 3 | 1, 2, 3 | --
I/P Fuse Block Ground | -- | 1, 2, 3 | 1, 2, 3 | --
1. Door Lock Malfunction 2. Driver Door Unlock Malfunction 3. Door Unlock Malfunction

### Circuit/System Description

The body control module (BCM) controls the door lock, passenger door unlock and driver door unlock relays. Voltage is applied to the appropriate relay through the door lock/unlock control circuit when the BCM senses a door lock/unlock switch activation or a keyless entry lock or unlock command.

### Conditions for Running the DTC

The system voltage is 9-18 volts.

### Conditions for Setting the DTC

#### B3125 00

The BCM detects a short to ground on the LT/UNLCK relay control circuit.

#### B3130 00

The BCM detects a short to ground on the UNLCK relay control circuit.

#### B3135 00

The BCM detects a short to ground on the LCK relay control circuit.

### Action Taken When the DTC Sets

The power door locks will be inoperative

### Conditions for Clearing the DTC

• | This DTC will be current for as long as the fault is present.

• | When the fault is no longer present, the DTC will be a history DTC.

• | A history DTC will clear after 50 ignition cycles.

### 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

Command the driver door and passenger door lock actuators to LOCK and UNLOCK with the scan tool, the doors should perform the LOCK and UNLOCK function.

⇒ | If B3125 00 is current, refer to LT/UNLCK Relay Control Circuit Malfunction.

⇒ | If B3130 00 is current, refer to UNLCK Relay Control Circuit Malfunction.

⇒ | If B3135 00 is current, refer to LCK Relay Control Circuit Malfunction

### Circuit/System Testing

#### LT/UNLCK Relay Control Circuit Malfunction

1. Ignition OFF, disconnect the LT/UNLCK relay.
2. Connect a test lamp between the control circuit terminal 85 and the B+ circuit terminal 86.
3. Command the driver door to UNLOCK with a scan tool. The test lamp should briefly illuminate when commanding the UNLOCK state.

⇒ | If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.

⇒ | If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the BCM.

4. If all circuits test normal, test or replace the LT/UNLCK relay.

#### UNLCK Relay Control Circuit Malfunction

1. Ignition OFF, disconnect the UNLCK relay.
2. Connect a test lamp between the control circuit terminal 85 and the B+ circuit terminal 86.
3. Command the rear doors to UNLOCK with a scan tool. The test lamp should briefly illuminate when commanding the UNLOCK state.

⇒ | If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.

⇒ | If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the BCM.

4. If all circuits test normal, test or replace the UNLCK relay.

#### LCK Relay Control Circuit Malfunction

1. Ignition OFF, disconnect the LCK relay.
2. Connect a test lamp between the control circuit terminal 85 and the ground circuit terminal 86.
3. Command the rear doors LOCK with a scan tool. The test lamp should briefly illuminate when commanding the LOCK state.

⇒ | If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.

⇒ | If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM.

4. If all circuits test normal, test or replace the LCK relay.

### Component Testing

1. Ignition OFF, disconnect the appropriate relay.
2. Test for 60-200 ohms between terminals 85 and 86.

⇒ | If not within the specified range, replace the relay.

3. Test for infinite resistance between the following terminals:

• | 30 and 86

• | 30 and 87

• | 30 and 85

• | 85 and 87

⇒ | If less than the specified value, replace the relay.

4. Test for less than 2 ohms between terminals 30 and 87A.

⇒ | If greater than the specified range, replace the relay.

5. Install a 3A fused jumper wire between relay terminal 85 and 12 volts. Install a jumper wire between relay terminal 86 and ground. Test for less than 2 ohms between terminals 30 and 87.

⇒ | If greater than the specified range, replace the relay.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Relay Replacement

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