B1310

Code

Other B — Body

Power Door Unlock Circuit Failure

Brand: Other

Type: B — Body

Views: UK: 30 EN: 42 RU: 37

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Page language: EN

Blown fuse or poor fuse connection in the door lock circuit
Open, high-resistance, or shorted wiring between module and door actuator/switch
Faulty door lock actuator (motor or internal switch)
Corroded or disconnected connector at the door or BCM
Faulty door lock/unlock switch or remote receiver
Ground problem at door or module

Verify customer complaint and reproduce the failure with key fob, door switches, and vehicle scan tool commands
Check for stored and freeze-frame DTCs with a capable scan tool
Inspect related fuses and fusible links for continuity and correct rating
Visually inspect door harness, connectors, and body harness grommet for damage or corrosion
Check for proper ground at door and BCM locations
Measure voltage and signal at the actuator connector while operating the unlock command

Typical system supply: ~12 V (battery voltage), measured at fuse and actuator power feed
Unlock command may be a 12 V supply or a ground-switched output depending on vehicle design
Actuator coil resistance typically in the range of ~5–30 ohms (varies by model) — expect low resistance, not open/infinite
Command pulses or drive current can be up to a few amps when activating the actuator
No voltage (open circuit) or constant short to ground/power are fault conditions

Interview and reproduce: Confirm which doors and which input methods (key fob, switches) fail.
Scan for codes: Read and record all related DTCs and BCM data/status using a scan tool.
Inspect fuses/relays: Check continuity and voltage at relevant fuses/relay terminals; replace if blown.
Visual/wiggle inspection: Examine harness from BCM to door through the pillar grommet for damage; wiggle while operating locks.
Connector check: Disconnect door actuator connector; inspect pins for corrosion, bent terminals, or water intrusion.
Voltage/ground tests: With actuator connected, command unlock and measure voltage at connector power and ground pins. Determine if the module is supplying drive (12 V or ground) as expected.
Actuator bench test: If no drive present at connector, disconnect actuator and bench-test it with a fused 12 V supply to confirm operation and coil resistance.
Wiring continuity: If actuator works but no command at door, test continuity between actuator connector and BCM, checking for shorts to chassis or battery.
Component swap or isolation: If wiring and actuator are good, consider replacing the door switch or BCM output driver after verifying software/configuration and programming status.
Clear codes and retest: After repair, clear DTCs and verify proper operation through multiple cycles and a full system check.