GM Service Manual Online
For 1990-2009 cars only

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 Descriptor

DTC B3125 00: Driver Door Only Unlock Circuit

Circuit/System Description

The body control module (BCM) energizes the driver door unlock relay coil through a low side drive control circuit. When the BCM receives an unlock message the driver door unlock relay control circuit is grounded energizing the driver door unlock relay coil.

Conditions for Running the DTC

    • Battery voltage is between 9-16 volts.
    • The BCM has attempted to energize the unlock relay.

Conditions for Setting the DTC

The driver door unlock relay control circuit is shorted to voltage.

Action Taken When the DTC Sets

The BCM will not attempt unlock operation.

Conditions for Clearing the DTC

    • When the output request is not active the DTC will be a history status code.
    • The history code will clear after 50 fault free ignition cycles or by using the scan tool clear DTCs feature.

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 Testing

  1. Disconnect the BCM connector X7 and connect a test lamp from terminal 6 to ground.
  2. Ignition ON, verify that the test lamp does not illuminate.
  3. If the test lamp illuminates test the control circuit for a short to voltage. If the circuit tests normal replace the IP fuse block.
  4. If the circuits test normal replace the BCM.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Instrument Panel Electrical Center or Junction Block Replacement - Left Side
    •  Control Module References for BCM replacement, programming, and setup.