Code
B1300
Other
B — Body
Power Door Lock Circuit Failure
AI status
Completed
Completed
100%
Causes
- Blown fuse or faulty relay for door locks
- Open, short to ground or short to battery in lock wiring harness or connector
- Corroded or loose connector at door lock actuator or BCM
- Failed door lock actuator (motor or internal switch)
- Faulty body control module (BCM) or door module
- Water intrusion or mechanical binding in lock mechanism
Symptoms
- One or more door(s) do not lock or unlock with switch/key/remote
- Intermittent lock operation or works only with force/specific conditions
- Clicking from door but lock does not move (actuator stuck)
- Other doors work while one door fails
- Blown fuse recurring when attempting to operate locks
- Battery drain or lock actuator running continuously in some cases
What to check
- Retrieve stored DTCs and freeze frame with OBD or factory scan tool
- Visually inspect fuses, relays and door harness at hinge for damage or corrosion
- Inspect door lock actuator connector and pins for corrosion or bent pins
- Operate locks while backprobing actuator connector to observe voltage/ground change
- Wiggle door harness and connectors while operating to reproduce fault
- Measure actuator resistance and current draw with door removed
Signal parameters
- Supply voltage: nominal battery voltage ~12.0–14.5 V at rest and during operation
- Actuator coil resistance (typical): low single digits to tens of ohms (commonly ~5–30 Ω) — varies by design
- Actuator operating current (typical): 0.5–6 A peak during movement (dependent on actuator design)
- Control signals: some systems use simple polarity reversal; others use BCM PWM output — PWM frequency varies by manufacturer (typical tens to a few hundred Hz)
- Expected behavior: voltage on one pin and ground on the other when driven, or polarity reversal between lock/unlock commands
Diagnostic algorithm
- Record code(s) and vehicle history; confirm affected door(s) and symptoms
- Visually inspect fuses and relays; replace blown fuse and test operation (note: do not replace fuse repeatedly without diagnosing short)
- Inspect door-to-body harness at hinge and connector for wear, corrosion, pin damage; repair or replace as needed
- With a multimeter, measure battery voltage at actuator connector; command lock/unlock and observe changes. Backprobe to avoid disturbing connector
- Measure actuator coil resistance with connector disconnected; compare to typical range. If open or very high, actuator likely failed
- Apply 12V direct to actuator motor briefly to verify mechanical operation (use insulated leads and correct polarity); if it operates, problem is wiring/control; if not, replace actuator
- Perform continuity and short-to-ground/battery tests on wiring between actuator and BCM; repair any shorted or open circuits
- Check BCM output using a scan tool or scope; verify correct output waveform/polarity when commanding locks. If BCM output absent but inputs correct, suspect BCM/module fault
- After repairs, clear codes and test multiple cycles of lock/unlock; monitor for recurrence and re-scan for codes
Likely causes
- Damaged wiring or chafed harness at hinge/door jamb (most common)
- Failed door lock actuator at the affected door
- Corroded connector at the actuator or body harness
- Blown fuse or failed relay supplying the lock circuit
Fault status
Status
Power door lock circuit failure detected. Possible open/short in wiring, bad connector, failed actuator, blown fuse, or BCM/door module fault.
Repair difficulty: Medium
Diagnostic time: 1.0-2.5 hours
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