B1B84

Code

Generic B — Body

Body Control Module — Passenger Door Unlock Circuit Fault

Brand: Generic

Type: B — Body

Views: UK: 9 EN: 13 RU: 10

AI status

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Page language: EN

Causes

Open or short in passenger door unlock wiring (to ground or battery)
Failed passenger door unlock actuator/servo
Poor connector contact or corroded terminals at door harness or BCM
Blown fuse or fusible link for door lock circuit
Faulty BCM output driver
Intermittent wiring damage (pinch, chafe) or water intrusion

Symptoms

Passenger door does not unlock using key fob, door switch, or central unlock command
Intermittent passenger door unlock operation
Other doors unlock normally while passenger door fails
Related diagnostic trouble codes present (BCM or communication codes)
Possible clicking/noise from actuator or no response at all

What to check

Scan BCM and network for active and stored codes; record freeze frame and status bits
Verify vehicle battery voltage is within specification
Inspect fuses and fusible links for door lock circuits
Visually inspect passenger door connector, harness through the door boot, and actuator for corrosion/damage
Command passenger door unlock from diagnostic tool and observe behavior
Backprobe actuator/connector while commanding unlock: verify expected voltage and ground signal

Signal parameters

Unlock command voltage at actuator: typically approx. battery voltage when commanded
Ground continuity from actuator to chassis ground
Actuator coil/servo resistance (ohms) — compare to spec
Activation current (amps) — look for unusually high or zero current
CAN/Local network messages: unlock command present at time of event
BCM output pin voltage/state when unlocked vs. not commanded

Diagnostic algorithm

Retrieve freeze frame and all related codes; note whether code is current or historic.
Check battery voltage and relevant fuses; replace blown fuses as needed and retest.
Visually inspect passenger door wiring, connectors and actuator for corrosion, damage or water ingress; repair any damage.
With connector connected, command unlock from a scan tool while monitoring voltage at the actuator connector: • If correct voltage present but actuator does not move, remove actuator and bench test or measure resistance/current. • If no voltage present, proceed to BCM output checks.
If the actuator shows open or abnormal resistance/current, replace the actuator and retest.
If no voltage at actuator, backprobe at BCM output (or junction) and verify whether BCM is commanding output. If BCM commands but voltage absent at harness, inspect wiring/connector between BCM and door for opens/shorts and repair.
If wiring is good and BCM does not command output when it should, check related inputs (door switch, lock/unlock request signals, ignition state, CAN messages). Verify BCM ground and supply voltages.
If BCM output driver appears faulty (short to ground or open), consider BCM repair or replacement after confirming wiring and actuator are good.
Clear codes and perform multiple lock/unlock cycles and full system test to confirm repair. Retest for intermittent faults by flexing harness in the door boot while commanding unlock.

Likely causes

Corroded or loose connector at passenger door latch/actuator
Failed actuator motor or solenoid with high current draw or open circuit
Damaged wiring in the door harness near the hinge/boot
BCM output transistor failed (short or open)
Blown fuse supplying the door lock/BCM output circuit

Fault status

⚠️ Status

BCM detected an abnormal condition on the passenger door unlock circuit (open/short/excessive load or intermittent connection) while commanding an unlock. Fault recorded when output response did not match expected electrical parameters.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.0 hours