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: Left Front/Driver Door Only Unlock Circuit
DTC B3130: All Door Unlock Circuit
DTC B3135: 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 | -- | --
Door Unlock Relay Control | B3130 | B3130 | B3130 | --
Driver Door Relay Unlock Control | B3125 | B3125 | B3125 | --
Door Lock Relay Control | B3135 | B3135 | -- | --
Driver Door Lock Switch Lock Signal | B3150 | B3150 | B3150 | --
Driver Door Lock Switch Unlock Signal | B3140 | B3140 | B3140 | --
Passenger Door Lock Switch Lock Signal | B3155 | B3155 | B3155 | --
Passenger Door Lock Switch Unlock Signal | B3145 | B3145 | B3145 | --
Door Lock Switch Ground | -- | 1,2,3 | 1,2,3 | --
I/P Fuse Block Ground | -- | 1,2,3 | 1,2,3 | --
1. Door Locks Inoperative 2. Driver Door Unlock Inoperative 3. Door Unlock Inoperative

### Circuit/System Description

The body control module (BCM), upon receipt of a lock switch lock signal, will switch the all lock relay control circuit to battery positive voltage. This will energize the lock relay. The remaining unlock relays receive voltage from the underhood fuse block, the BCM upon receipt of a unlock signal or driver door unlock signal will switch the appropriate unlock relay to ground. This will energize the appropriate unlock relay.

### Conditions for Running the DTC

The system voltage must be between 9-16 volts.

### Conditions for Setting the DTC

#### B3125

The BCM detects a fault in the driver door unlock control circuit while commanding the driver door unlock relay.

#### B3130

The BCM detects a fault in the door unlock control circuit while commanding the door unlock relay.

#### B3135

The BCM detects a fault in the door lock control circuit while commanding the door lock relay.

### Action Taken When the DTC Sets

• | The BCM stores the DTC to memory.

• | The power door locks will not operate.

### Conditions for Clearing the DTC

• | This DTC will change from current to history when the fault is no longer present.

• | A history DTC will clear after 100 consecutive ignition cycles if the condition for the malfunction is no longer present.

### Reference Information

#### Schematic Reference

• | Door Lock/Indicator Schematics

• | Release Systems Schematics

#### Connector End View Reference

Vehicle Access Connector End Views

#### Description and Operation

• | Power Door Locks Description and Operation

• | Rear Hatch/Gate Description and Operation

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Scan Tool Reference

• | Scan Tool Data List

• | Scan Tool Data Definitions

• | Scan Tool Output Controls

### Circuit/System Testing

1. Ignition OFF, disconnect the harness connector C3 at the I/P fuse block.
2. Connect a test lamp between the control circuit terminal 42 and ground.
3. Ignition ON, command the lock rear doors ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.

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

⇒ | 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.

4. Connect a test lamp between the control circuit terminal 8 and B+.
5. Command the driver door unlock ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.

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

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

6. Connect a test lamp between the control circuit terminal 41 and B+.
7. Command the unlock rear doors ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.

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

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

8. If all circuits tests normal, replace the I/P fuse block.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for BCM replacement, setup, and programming

Instrument Panel Electrical Center or Junction Block Replacement