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 B3130 00: All Door Unlock Circuit

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

I/P Fuse Block B+

3, 4

3, 4

--

--

Driver Door Latch Control

1

1

1

--

Passenger Door Latch Control

2

2

2

--

Lock/Unlock PCB Relay Control

B3130 00 or B3135 00

B3130 00 or B3135 00

B3130 00 or B3135 00

--

Rear Door Latch Control

3, 4

3, 4

3, 4

--

I/P Fuse Block Ground

--

3, 4

3, 4

--

1. Driver Door Latch Malfunction

2. Passenger Door Latch Malfunction

3. Rear Door Unlock Inoperative

4. Rear Door Lock Inoperative

Circuit/System Description

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

    • 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

Vehicle Access 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

    •  Scan Tool Data Definitions
    •  Scan Tool Data List
    •  Scan Tool Output Controls

Circuit/System Verification

Command the rear doors lock to LOCK and UNLOCK with a scan tool, the doors should perform the LOCK and UNLOCK function.

Circuit/System Testing

  1. Ignition OFF, disconnect the C3 harness connector at the I/P fuse block.
  2. Connect a test lamp between the control circuit terminal A3 and B+.
  3. Ignition ON, command the doors to UNLOCK with a scan tool, the test lamp should illuminate during the UNLOCK command.
  4. 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.
  5. If the circuit tests normal, replace the I/P fuse block.

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