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 B3142: Unlock Switch Circuit Low
DTC B3143: Unlock Switch Circuit High

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Driver Door Lock and Window Switch B+ | 1, 2 | 1, 2 | -- | --
Passenger Door Switch Unlock Signal | 1, 2 | 2 | 2 | --
Door Lock Actuator Control | 1 | 1 | 1 | --
Door Unlock Control | B3142 | B3143 | B3143 | --
Passenger Door Lock Switch Lock Control | B3152 | B3153 | B3153 | --
Driver Door Lock and Window Switch Ground | -- | 1, 2 | 1, 2 | --
Passenger Door Lock and Window Switch Ground | -- | 2 | 2 | --
1. Door Lock Malfunction 2. Door Lock Switch Malfunction

### Circuit/System Description

The driver door lock actuator unlock control circuit is a dedicated control circuit used only for the driver door lock actuator motor. This is done so that the driver door may be unlocked by itself using a keyless entry transmitter or an automatic door unlock function, if programmed.

### Conditions for Running the DTC

Battery voltage must be between 9-16 volts.

### Conditions for Setting the DTC

#### B3142

The body control module (BCM) detects a short to ground on the door unlock control circuit for greater than 60 seconds.

#### B3143

The BCM detects a short to voltage or an open/high resistance in the door unlock control circuit for greater than 60 seconds.

### Action Taken When the DTC Sets

The driver door lock actuator will not unlock when using the keyless entry transmitter.

### Conditions for Clearing the DTC

• | The 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

1. Ignition ON, command the driver door to UNLOCK and all doors to LOCK with a scan tool. The driver door should unlock and all doors should lock.
2. Command the driver door to UNLOCK and all doors to LOCK with the keyless entry transmitter, the driver door should unlock and all doors should lock.

⇒ | If the keyless entry transmitter is inoperative, refer to Keyless Entry System Inoperative .

### Circuit/System Testing

1. Ignition OFF, disconnect the harness connector X2 at the driver door lock switch.
2. Connect a test lamp between the control circuit terminal 13 and B+.
3. Ignition ON, command the Driver Door Unlock with a scan tool. The test lamp should illuminate when commanding the UNLOCK state.

⇒ | 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 an open/high resistance. If the circuit tests normal, replace the BCM.

4. If the circuit tests normal, replace the driver door lock switch.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for BCM replacement, setup and programming