B3135
DTC B3125, B3130, or B3135
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) 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/System Description
The body control module (BCM), upon receipt of a lock switch lock signal, will switch the Door Lock Relay Control circuit to battery positive voltage. This will energize the LOCK relay. The remaining unlock relays receive voltage from the underhood fuse block, the BCM upon receipt of a unlock signal or driver door unlock signal will switch the appropriate unlock relay to ground. This will energize the appropriate unlock relay unlocking the appropriate doors.
Conditions for Running the DTC
The system voltage must be between 9-16 volts.
Conditions for Setting the DTC
B3125 00
The BCM detects a fault in the driver door unlock control circuit while commanding the DRIVER UNLOCK relay.
B3130 00
The BCM detects a fault in the door unlock control circuit while commanding the UNLOCK relay.
B3135 00
The BCM detects a fault in the door lock control circuit while commanding the LOCK relay.
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 be a history DTC.
* A history DTC will clear after 50 ignition cycles.
Reference Information
Schematic Reference
Door Lock/Indicator Schematics (Door Lock/Indicator Schematics)
Connector End View Reference
Component Connector End Views (Connector 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
Ignition ON, command the driver door and passenger door lock actuators to LOCK and UNLOCK with the scan tool, the doors should perform the LOCK and UNLOCK functions.
Circuit/System Testing
1. Ignition OFF, disconnect the X1 harness connector at the I/P fuse block.
2. Connect a test lamp between control circuit terminal K4 and ground.
3. Ignition ON, command the Lock Rear Doors ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
• If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM.
• 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.
4. Connect a test lamp between control circuit terminal K6 and B+.
5. Command the Driver Door Unlock ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
• 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 and open/high resistance. If the circuit tests normal, replace the BCM.
6. Connect a test lamp between the control circuit terminal K5 and B+.
7. Command the Unlock Rear Doors ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
• 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 and open/high resistance. If the circuit tests normal, replace the BCM.
8. If all circuits test normal, replace the I/P fuse block.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Instrument Panel Electrical Center or Junction Block Replacement - Right Side (Impala) (Instrument Panel Electrical Center or Junction Block Replacement - Right Side (Impala))
* Control Module References (Programming and Relearning) for BCM replacement, setup, and programming