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 Descriptors

DTC B3140: Driver Unlock Switch Circuit Short to Ground

DTC B3145: Passenger Unlock Switch Circuit Short to Ground

DTC B3150: Driver Lock Switch Circuit Short to Ground

DTC B3155: Right Front Lock Switch Circuit Short to Ground

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

I/P Fuse Block B+

1, 2, 3

1, 2, 3

--

--

Door Latch Control

1, 2, 3

1, 2, 3

--

--

Doors Unlock Control

B3130

B3130

B3130

--

LF Door Unlock Control

B3125

B3125

B3125

--

Doors Locked Control

B3135

B3135

--

--

Left Lock Switch Signal

B3150

B3150

B3150

--

Left Unlock Switch Signal

B3140

B3140

B3140

--

Right Lock Switch Signal

B3155

B3155

B3155

--

Right Unlock Switch Signal

B3145

B3145

B3145

--

Door Lock Switch Ground

--

1, 2, 3

1, 2, 3

--

I/P Fuse Block Ground

--

1, 2, 3

1, 2, 3

--

1. Door Lock Inoperative

2. Driver Door Unlock Inoperative

3. Door Unlock Inoperative

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 senses a door lock/unlock switch activation or a keyless entry lock or unlock command.

Conditions for Running the DTC

The system voltage must be between 9-16 volts.

Conditions for Setting the DTC

B3140 or B3150

The BCM detects a short to ground in the Left Lock Switch or Unlock Switch signal circuits.

B3145 or B3155

The BDM detects a short to ground in the Right Lock Switch or Unlock Switch signal circuits.

Action Taken When the DTC Sets

    • The BCM stores the DTC to memory.
    • The power door locks will not operate.

Conditions for Clearing the DTC

    • This DTC will change from current to history when the fault is no longer present.
    • A history DTC will clear after 100 consecutive ignition cycles if the condition for the malfunction is no longer present.
    • The technician issues a scan tool CLEAR DTCs command.

Reference Information

Schematic Reference

Door Lock/Indicator Schematics

Connector End View Reference

    •  Vehicle Access Connector End Views
    •  Data Communication 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 List
    •  Scan Tool Data Definitions
    •  Scan Tool Output Controls

Circuit/System Testing

  1. Ignition OFF, disconnect the harness connector at the appropriate Door Lock Switch.
  2. Ignition ON, verify the scan tool Lock Sw is Inactive.
  3. If not the specified value, test the signal circuit terminal E for a short to ground. If the circuit tests normal, replace the BCM.
  4. Verify the scan tool Unlock Sw is Inactive.
  5. If not the specified value, test the signal circuit terminal D for a short to ground. If the circuit tests normal, replace the BCM.
  6. If all circuits test normal, test or replace the appropriate door lock switch.

Component Testing

  1. Ignition OFF, disconnect the harness connector at the applicable door lock switch.
  2. Test for infinite resistance between the signal terminals D and E and the ground terminal B with the switch in the open position.
  3. If less than infinite resistance, replace the applicable door lock switch.
  4. Test for less than 2 ohms of resistance between the signal terminal D and the ground terminal B with the switch in the unlock position.
  5. If greater than 2 ohms, replace the applicable door lock switch.
  6. Test for less than 2 ohms of resistance between the signal terminal E and the ground terminal B with the switch in the lock position.
  7. If greater than 2 ohms, replace the applicable door lock switch

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for BCM replacement, setup, and programming