Code
B1320
Other
B — Body
Driver Door Ajar Circuit Open
AI status
Completed
Completed
100%
Causes
- Open circuit in driver door ajar wiring (broken conductor or connector open)
- Faulty driver door ajar (door latch) switch
- Disconnected or corroded connector at switch or BCM
- Damaged wiring through the door jamb/hinge (pinch or flex point)
- Aftermarket alarm/central locking modification incorrectly wired
- BCM or instrument cluster input fault (less common)
Symptoms
- Driver door ajar warning lamp or message illuminated
- Dome/interior lights may stay on or behave oddly
- Battery drain if interior lights remain on
- Central locking or alarm may not arm or may report door open
- Door-ajar chime or warning tone
- Door open indicator on instrument cluster or driver information center
What to check
- Scan vehicle to confirm DTC, freeze frame and ignition cycle count
- Visually inspect driver door latch/switch and connector for damage or corrosion
- Inspect wiring in door jamb/boot for breaks, chafing or pinched conductors
- Wiggle door harness while observing connector and cluster for changes
- Backprobe switch connector and measure voltage/continuity with door open and closed
- Check for aftermarket devices tied into door-ajar circuit
Signal parameters
- Expected logical behavior: closed door = switch provides continuity (to ground or signal reference); open door = open circuit or pulled to supply via BCM pull-up
- Typical voltage behavior (generic): door closed = ~0–1 V if switch grounds the circuit; door open = ~8–12 V (pulled up by BCM) or open/infinite resistance
- Continuity: closed door should show near 0 Ω between switch terminal and reference (ground or BCM input); open door should show infinite/OL
- Resistance: closed state typically
Diagnostic algorithm
- Retrieve and record the DTC and any related codes; note freeze frame/live data for door-ajar input if available.
- Visually inspect the driver door latch/switch and connector for corrosion, damage, or signs of water entry. Ensure connector is fully seated.
- With ignition ON (engine off) backprobe the switch connector and observe the signal while opening and closing the door. Note voltages and changes.
- Check continuity between the switch terminal and the BCM input pin with the door closed. If continuity is lost, suspect wiring or connector.
- Inspect the harness through the door jamb boot; flex the boot while monitoring continuity to reproduce intermittent opens. Repair any broken conductors.
- If switch shows no continuity when it should, remove and bench-test/replace the door latch/switch assembly.
- If wiring and switch test good, inspect the BCM connector and wiring for corrosion or open circuit. Backprobe at the BCM and confirm expected voltages/continuity.
- If all wiring and switch are good but signal is still incorrect, consider BCM/input module fault and consult manufacturer procedures before replacing.
- After repairs, clear codes and perform several open/close cycles and a short drive/ignition cycles to verify the code does not return.
Likely causes
- Broken or chafed wire in harness at door hinge/boot
- Loose or pushed-back pin in the switch-to-harness connector
- Corroded switch terminals from water intrusion
- Door latch assembly failed electrically
- Connector not fully seated after service
- Intermittent open caused by movement (wiring fatigue)
Fault status
Status
Open circuit detected in driver door ajar switch circuit — BCM reports no continuity or expected signal from driver door sensor.
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
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