GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2009 🢒 Caprice WM 🢒 Body Systems 🢒 Vehicle Access 🢒 DTC B3125, B3130, or B3135

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 00: Left Front/Driver Door Only Unlock Circuit

DTC B3130 00: All Door Unlock Circuit

DTC B3135 00: 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

1

--

--

Door Lock Switch Lock Signal

B3150 00

2

2

--

Door Lock Switch Unlock Signal

B3140 00

2

2

--

All Lock Relay Control

B3135 00

B3135 00

1

--

Door Latch Assembly Control

1

1

1

--

Driver Unlock Relay Control

B3125 00

B3125 00

B3125 00

--

Passenger Unlock Relay Control

B3130 00

B3130 00

B3130 00

--

Window/Door Lock Switch Ground

--

2

2

--

Relay Ground

--

1

1

--

1. Door Lock Malfunction

2. Door Lock Switch Malfunction

Circuit/System Description

The body control module (BCM) controls the door lock, passenger door unlock and driver door unlock relays. Voltage is applied to the appropriate relay through the door lock/unlock control circuit when the BCM detects a door lock/unlock switch activation or a keyless entry lock or unlock command.

Conditions for Running the DTC

The system voltage is 9-16 volts.

Conditions for Setting the DTC

B3125 00

The BCM detects a fault on the DRIVER UNLOCK relay control circuit.

B3130 00

The BCM detects a fault on the PASS UNLOCK relay control circuit.

B3135 00

The BCM detects a fault on the ALL LOCK relay control circuit.

Action Taken When the DTC Sets

The power door locks will malfunction.

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 become 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

Ignition ON, command the All Doors Unlock/Lock with the scan tool, all doors should perform the LOCK and UNLOCK function.

⇒If B3125 00 is set, refer to DRIVER UNLOCK Relay Control Malfunction.
⇒If B3130 00 is set, refer to PASS UNLOCK Relay Control Malfunction.
⇒If B3135 00 is set, refer to ALL LOCK Relay Control Malfunction.

Circuit/System Testing

DRIVER UNLOCK Relay Control Malfunction

  1. Ignition OFF, disconnect the DRIVER UNLOCK relay.
  2. Connect a test lamp between the control circuit terminal 85 and the B+ circuit terminal 86.
  3. Ignition ON, command the Driver Door Unlock with a scan tool. The test lamp should briefly illuminate when commanding the UNLOCK state.
    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.
  4. If all circuits test normal, test or replace the DRIVER UNLOCK relay.

PASS UNLOCK Relay Control Malfunction

  1. Ignition OFF, disconnect the PASS UNLOCK relay.
  2. Connect a test lamp between the control circuit terminal 85 and the B+ circuit terminal 86.
  3. Ignition ON, command the All Doors Unlock with a scan tool. The test lamp should briefly illuminate when commanding the UNLOCK state.
    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.
  4. If all circuits test normal, test or replace the PASS UNLOCK relay.

ALL LOCK Relay Control Malfunction

  1. Ignition OFF, disconnect the ALL LOCK relay.
  2. Connect a test lamp between the control circuit terminal 85 and the ground circuit terminal 86.
  3. Ignition ON, command the All Doors Lock with a scan tool. The test lamp should briefly illuminate when commanding the LOCK state.
    4. ⇒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.
    ⇒If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM.
  4. If all circuits test normal, test or replace the ALL LOCK relay.

Component Testing
  1. Ignition OFF, disconnect the appropriate relay.
  2. Test for 60-200 Ω between terminals 85 and 86.
    3. ⇒If not within the specified range, replace the relay.
  3. Test for infinite resistance between the following terminals:
    4. • 30 and 86
    • 30 and 87
    • 30 and 85
    • 85 and 87
    ⇒If less than the specified value, replace the relay.
  4. Test for less than 2 Ω between terminals 30 and 87A.
    5. ⇒If greater than the specified range, replace the relay.
  5. Install a 3A fused jumper wire between relay terminal 85 and 12V. Install a jumper wire between relay terminal 86 and ground. Test for less than 2 Ω between terminals 30 and 87.
    6. ⇒If greater than specified range, replace the relay

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Relay Replacement
    •  Control Module References for BCM replacement, setup, and programming