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Home / DTC / B29C6 — Door unlock signal:open timeout

B29C6 — Door unlock signal:open timeout

Detailed page for trouble code B29C6.

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Code

B29C6

MITSUBISHI B — Body

Door unlock signal:open timeout

Brand: MITSUBISHI
Type: B — Body
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Faulty door lock/unlock actuator stuck in the unlocked position
  • Short or open in unlock signal wiring (short to voltage or ground)
  • Corroded or loose connector at actuator, door switch, or BCM
  • Faulty door lock switch or keyless entry switch
  • High resistance or poor ground in the circuit
  • BCM or keyless entry module software/firmware fault or internal failure

Symptoms

  • Door(s) fail to unlock or remain unlocked
  • Intermittent or non-functional remote/key fob unlock operation
  • Door unlock takes longer than normal or requires multiple attempts
  • Chimes or warning messages related to door status
  • DTC stored and possibly other related B-codes present

What to check

  • Read and record all stored/active/ pending codes with an OEM-capable scan tool; check freeze frame data
  • Monitor live data for door unlock signal(s) while operating key fob and interior switches
  • Visually inspect door harness and connectors for damage, corrosion, or water ingress
  • Check fuses and power/ground supplies to BCM, keyless entry module, and door actuator
  • Measure voltage at the unlock signal wire and actuator connector during command
  • Perform continuity/resistance checks on unlock circuit wiring between BCM and actuator

Signal parameters

  • Expected idle voltage: near 0 V (signal inactive) or battery voltage depending on design; verify with factory data
  • Active command voltage: typically battery voltage (~12 V) or switched ground depending on system design
  • Switching behavior: unlock signal should change state within fractions of a second when commanded
  • Timeout behavior: control module expects the unlock signal to return to inactive within a short interval (usually < a few seconds)

Diagnostic algorithm

  1. Obtain full DTC list and freeze-frame; note which door circuits are affected.
  2. Clear code(s) and reproduce condition while watching live data for door unlock signal and related inputs.
  3. Operate unlock via driver switch, passenger switch, and key fob one at a time to isolate which command sources affect the signal.
  4. With a DVOM or scope, backprobe the unlock signal wire at the BCM and at the door actuator. Verify correct voltage transitions and that the signal returns to inactive after the command.
  5. Inspect and wiggle the door harness and connectors while monitoring the signal for intermittent faults; repair any damaged wiring or connectors.
  6. Measure actuator current draw during operation. Excessive or no current suggests a shorted or open actuator respectively. Bench-test actuator if necessary.
  7. Check grounds for proper continuity to chassis ground; clean and tighten ground points as required.
  8. If wiring and actuator check OK, verify BCM outputs and inputs. Reflash or update module software if a known software issue exists per service bulletins.
  9. If BCM output appears faulty after eliminating wiring and actuator faults, replace or repair the BCM/module per manufacturer procedure.
  10. After repairs, clear codes and confirm repeated successful unlock operations and no reappearance of B29C6.

Likely causes

  • Damaged wiring or connector (pin corrosion, bent pins) at the door harness
  • Door lock actuator mechanically binding or electrical coil shorted
  • Faulty door unlock switch or door ajar switch reporting incorrect state
  • Intermittent ground connection causing signal to remain active
  • Faulty BCM or module output stage (less common)

Fault status

⚠️ Status
Door unlock signal remained active past allowed timeout — indicates unlock circuit did not return to expected state within specified time.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

B29C5 B29C7 B2900 B2901 B2A00
406

Browse 406 MITSUBISHI manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

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