Code
B2732
HUMMER
B — Body
Rear door lock/unlock circuit fault
AI status
Completed
Completed
100%
Causes
- Open or shorted wiring in rear door harness (often at door hinge/b-pillar)
- Corroded or loose connector at rear door, latch/actuator, or body harness
- Failed rear door lock actuator (motor or internal switch)
- Blown fuse or defective relay supplying the lock circuit
- Faulty Body Control Module (BCM) or driver circuit
- Water intrusion or physical damage at door latch area
Symptoms
- Rear door will not lock or unlock with key fob, door switch, or central locking
- Intermittent rear door locking/unlocking operation
- Audible clicking or no sound from rear door when commanding lock/unlock
- Other doors work normally while rear door does not
- Related DTC(s) stored in BCM; possible loss of remote/central lock function
What to check
- Retrieve and record all related DTCs and freeze-frame data with a diagnostic scanner
- Check vehicle battery voltage (low voltage can cause faults)
- Visually inspect fuses and relays for the locking circuits; replace if blown
- Inspect rear door & B-pillar harness for chafing, pinched wires, broken strands, or water damage
- Unplug connectors at rear door latch/actuator and BCM to check for corrosion, bent pins, or water intrusion
- Operate lock/unlock while listening at the rear door for actuator operation
Signal parameters
- Supply voltage to lock circuit: ~12 V (battery voltage) with ignition on; verify actual battery voltage before testing
- Actuator coil resistance (typical): ~2–30 ohms (varies by design) — consult factory spec for exact value
- Control signal behavior: BCM may switch to ground (0 V) or provide a +12 V pulse to actuators; expected open-circuit voltage should be battery voltage when inactive
- No continuity to chassis ground on a circuit that is not intended to be grounded except when commanded (verify expected wiring using wiring diagram)
Diagnostic algorithm
- Connect a capable scan tool, read and record DTC B2732 and any related codes; clear codes and attempt to reinitialize to see if code returns.
- Verify battery voltage ≥12.0 V. Recheck fuses/relays for the lock circuit; replace as needed.
- Visually inspect rear door harness, door jamb, and connectors for damage or corrosion. Repair any visible wiring damage.
- With connector disconnected at the rear door actuator, measure actuator coil resistance. Compare to service spec; if out of range, replace actuator.
- Reconnect actuator. Backprobe the actuator control connector. Command lock/unlock from scan tool while observing voltage: verify supply and control signals (look for pulses or change to ground).
- If no command voltage at actuator connector but BCM grounds/sends signal per scan tool data, suspect connector/wiring between BCM and door. Check continuity between BCM pin and actuator pin; repair open/shorts.
- If control voltage present at actuator but actuator does not respond, bench-test actuator with 12 V to confirm operation; replace actuator if required.
- If short to battery or ground is suspected, isolate sections of harness and use an ammeter/ohmmeter to locate short. Repair wiring or replace harness sections.
- After repairs, clear DTCs and perform multiple lock/unlock cycles with scan tool monitoring to confirm fault is gone and no new codes set.
- If all wiring and actuator test good but code persists and BCM outputs are abnormal, consider BCM replacement or reprogramming only after confirming root cause and consult factory procedure.
Likely causes
- Broken or chafed wires at the door jamb due to repeated door movement
- Corrosion inside the rear door connector or latch connector
- Failed lock actuator motor (stuck or high resistance)
- Blown or poor fuse/relay connection supplying the lock circuit
- BCM output driver failed after a short or water exposure
Fault status
Status
BCM reports a fault in the rear door lock/unlock circuit (open, short, high resistance, or intermittent connection). Further electrical diagnosis required to identify component or wiring fault.
Repair difficulty: Medium
Diagnostic time: 1.0-2.5 hours
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Repair manuals
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138
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