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Home / DTC / B2789 — Release of left or right lock - circuit failure

B2789 — Release of left or right lock - circuit failure

Detailed page for trouble code B2789.

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Code

B2789

LAND ROVER B — Body

Release of left or right lock - circuit failure

Brand: LAND ROVER
Type: B — Body
Views: UK: 3 EN: 11 RU: 6
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Page language: EN

Causes

  • Broken, chafed or pinched wiring in the lock circuit
  • Corroded or loose connector at the door lock actuator or body harness
  • Failed door lock actuator/motor or solenoid
  • Failed BCM or driver stage (output transistor) on the BCM
  • Blown fuse or faulty relay supplying the lock circuit
  • Water ingress or corrosion in door/lock area

Symptoms

  • One door (left or right) fails to unlock or locks intermittently
  • No audible actuator movement or a single click from the door
  • Central locking operates partially or only from some inputs (key fob, door switch)
  • DTC stored and lamp or message may appear (depending on model)
  • Possible increased battery drain if short to ground exists

What to check

  • Retrieve and record all stored codes and freeze-frame data with a compatible scan tool and note which side (left/right) is reported.
  • Verify battery voltage (should be stable ~12–14V) before tests.
  • Operate the locks while observing behavior and listening for actuator noise.
  • Visually inspect fuses and relays for the central locking/BCM circuits.
  • Inspect door harness, grommet and connectors for corrosion, damage or water intrusion.
  • Wiggle test the harness/connector while operating lock to reproduce intermittent fault.

Signal parameters

  • Command voltage to actuator when unlocking: approx battery voltage (~9–14V) or switched ground depending on design
  • No-command voltage: near 0V (or float) at switched conductor
  • Actuator resistance: measurable ohms (varies by actuator) — infinite = open, near short = low ohms
  • Current draw when operated: actuator current in the amp range (abnormal high = seized/shorted)
  • Continuity:
  • Ground integrity: near 0V drop between chassis ground and actuator ground when commanded

Diagnostic algorithm

  1. Read and record DTCs and any related network/body codes. Note which side (left/right) is indicated.
  2. Verify battery voltage and disable any anti-theft precautions per service manual.
  3. Attempt to operate the lock while monitoring the actuator connector voltage with a backprobe or breakout harness. Observe behavior and voltage change when the BCM commands unlock.
  4. If command voltage is present at the door connector and the actuator does not move, disconnect connector and bench-test the actuator with a fused 12V supply to confirm failure.
  5. If no command voltage is present, trace wiring back to the BCM: check continuity, pin condition and for shorts to ground or battery. Perform wiggle tests through the door harness and grommet.
  6. Inspect and repair any damaged wiring, pins or connectors. Clean and secure connectors; replace grommets if water ingress is present.
  7. If wiring and actuator test good, check BCM output driver. Verify related relays/fuses and perform module communication checks. Replace or reprogram BCM only after confirming external circuit is good.
  8. Clear codes and re-test multiple cycles. Road test/operate locks repeatedly to confirm fault is resolved and code does not return.
  9. Refer to the vehicle-specific wiring diagrams, connector views and manufacturer service procedures for pinouts, expected values and safety precautions.

Likely causes

  • Open or short in the harness to the affected door lock
  • Corroded connector at the actuator or door harness splice
  • Failed actuator (stiff or no movement when power applied)
  • Faulty BCM output for the lock release circuit
  • Intermittent contact due to door hinge/chassis wiring flex

Fault status

⚠️ Status
Release of left or right lock - circuit failure (open/short/intermittent between BCM and door lock actuator).
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

B2788 B2790 B278A U0140 U0121
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