Power Door Locks Inoperative
Power Door Locks Inoperative
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) provide an overview of each diagnostic category.
Diagnostic Fault Information
Circuit/System Description
The DR LCK fuse supplies battery voltage to the body control module (BCM) for the power door lock system. The BCM supplies and monitors a reference voltage to the driver and passenger door lock switches through the door lock switch lock/unlock signal circuit. Each door lock switch receives ground at G300 which is also the ground for the door lock and unlock relays located in the BCM. When a door lock switch is placed in the lock position, the reference voltage is switched to ground and the BCM senses 0.0 volts on the door lock/unlock signal circuit. When a door lock switch is placed in the unlock position, the reference voltage is switched to ground through a 1.5k ohm resistor that is internal to each of the door lock switches and the BCM senses approximately 2.9 volts on the door lock/unlock signal circuit. The BCM interprets what position the activated door lock switch was placed in based on the voltage drop.
The BCM, upon receipt of a lock or unlock switch signal, will switch the appropriate door lock/unlock relay coil control circuit to ground causing the appropriate door lock/unlock relay to energize. With the relay energized, voltage is applied to the door lock actuator control circuit causing the door to either lock, or unlock depending on what command was received from the power door lock switch or remote control door lock receiver (RCDLR). When a power door lock/unlock relay is not energized, the switch contacts are normally grounded through the BCM which provides ground to the appropriate door lock actuator for the lock/unlock function being performed. The power door lock/unlock functions are performed by reversing the flow of voltage through the door lock actuator control circuits. The BCM has three internal drivers for the power door lock system. Driver door unlock, passenger door unlock and all door lock. This is done to isolate the driver door lock actuator so it can be unlocked separately from the passenger door.
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)
* Keyless Entry System Description and Operation (Keyless Entry System 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)
Circuit/System Verification
1. Ignition ON, with a scan tool observe the door lock switch parameter while activating the appropriate door lock switch to the LOCK and UNLOCK positions. The reading should change between IDLE, LOCK and UNLOCK.
• If the reading does not change as the switch is activated, refer to Power Door Lock Switch Malfunction.
2. Ignition ON, command the door latch to LOCK and UNLOCK with the scan tool, the door should LOCK and UNLOCK.
• If the door does not lock and unlock when changing between the commanded states, refer to Power Door Lock Malfunction.
Circuit/System Testing
Power Door Lock Switch Malfunction
1. Ignition OFF, disconnect the harness connector at the inoperative door lock switch.
2. Ignition OFF, verify that a test lamp illuminates between B+ and the ground circuit terminal A.
• If the test lamp does not illuminate, test the ground circuit for an open/high resistance.
3. Ignition ON, verify the scan tool door lock switch parameter is IDLE.
• If not the specified value, test the signal circuit terminal C for a short to ground. If the circuit tests normal, replace the BCM.
4. Install a 3-amp fused jumper wire between the signal circuit terminal C and the ground circuit terminal A. Verify the scan tool door lock switch parameter is LOCK.
• If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
5. If all circuits test normal, test or replace the appropriate door lock switch.
Power Door Lock Malfunction
1. Ignition OFF, disconnect the X4 harness connector at the BCM.
2. Ignition OFF, verify that a test lamp illuminates between B+ and the ground circuit terminal E12.
• If the test lamp does not illuminate, test the ground circuit for an open/high resistance.
3. Connect the X4 harness connector at the BCM.
4. Ignition OFF, disconnect the inoperative door lock actuator harness connector.
5. Ignition OFF, verify that a test lamp illuminates between B+ and the door lock actuator LOCK control circuit.
• If the test lamp does not illuminate, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
6. Ignition OFF, verify that a test lamp illuminates between B+ and the door lock actuator UNLOCK control circuit.
• If the test lamp does not illuminate, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
7. Connect a test lamp between the inoperative door lock actuator lock and unlock control circuits at the inoperative door lock actuator harness connector.
8. Ignition ON, perform the LOCK and UNLOCK functions with a scan tool. The test lamp should illuminate as the lock and unlock functions are performed.
• If the test lamp remains OFF during either of the commands and the circuit fuse is good, test for a short to ground on either control circuit. If the circuits test normal, replace the BCM.
• If the test lamp is always OFF and the circuit fuse is open, test the control circuits for a short to ground. If the circuits test normal, replace the BCM.
9. If all circuits test normal, test or replace the inoperative door lock actuator.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Door Lock Switch Replacement (Service and Repair)
* Front Side Door Lock Replacement (Front Side Door Lock Replacement)
* Control Module References (Programming and Relearning) for BCM replacement, setup, and programming