B0555

Code

Generic B — Body

Body Control Module: Door Lock Actuator Circuit Fault

Brand: Generic

Type: B — Body

Views: UK: 11 EN: 15 RU: 10

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One door or multiple doors fail to lock/unlock with key fob or interior switch
Intermittent or single-direction operation (locks but won’t unlock, or vice versa)
No audible actuator noise or only a faint click from the door
Blown fuse when trying to operate locks
Other body electrical anomalies or stored body module communication faults

Scan BCM and related modules for codes and freeze-frame data
Verify battery voltage (while cranking and at rest) — low voltage can cause faults
Inspect fuses and relays for the door lock circuits
Visually inspect wiring harness through the door jamb boot for chafing or breaks
Disconnect and inspect actuator and BCM connectors for corrosion, bent pins or water
Operate locks while listening for actuator noise to isolate which door is affected

Expected supply voltage at actuator connector: ~11–14 V when commanded (depends on battery state)
Driver signal: polarity switch or ground switching; some systems reverse polarity for lock vs unlock
Actuator current draw: typically 0.5–5 A during operation (varies by actuator size)
Static coil resistance (motor/windings): commonly in the low ohm range (single to tens of ohms); a very high or open reading indicates a fault
PWM-style drivers: may use a low-duty periodic control (tens to a few hundred Hz) — verify with scope when applicable

Retrieve stored codes from BCM and related modules; note occurrence count and freeze-frame.
Verify battery voltage >12 V and inspect fuses/relays for the door lock circuit; replace any blown fuses and retest.
Visually inspect wiring in the door hinge boot, connectors at the door lock actuator and BCM for damage, corrosion or loose pins.
With the door closed, command lock/unlock while listening and observing actuator response. Identify which door is at fault.
Back-probe the actuator connector while commanding lock/unlock: check for supply voltage and switching/ground signal. Compare to expected signal behavior (polarity change, pulse).
Measure actuator coil resistance with connector disconnected. An open or very high resistance indicates a bad actuator; a short to ground indicates wiring short.
If voltage is present at the connector but actuator does not run, bench-test the actuator directly from a 12 V source to confirm mechanical/electrical function.
If actuator is OK but no valid drive signal from BCM, check continuity from BCM pin to door connector and for intermittent breaks (wiggle test through door jamb).
If wiring and actuator are good but no drive or abnormal signals from BCM, inspect BCM grounds and power supplies; consider BCM software update or module replacement after verifying wiring.
Clear codes and re-test multiple cycles. Record results and re-scan for new codes.