B3142

DTC B3142 or B3143

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (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/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 ([1][2]Electrical Diagrams)
Connector End View Reference

Component Connector End Views (Component Connector End Views)
Description and Operation

Power Door Locks Description and Operation (Description and Operation)
Electrical Information Reference

* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)

Scan Tool Reference

Control Module References (Programming and Relearning) 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 (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 (Verification Tests) after completing the diagnostic procedure.


Control Module References (Programming and Relearning) for BCM replacement, setup and programming