Code
B1325
ALFA ROMEO
B — Body
Door open warning lamp circuit short to positive
Views:
UK: 4
EN: 8
RU: 7
AI status
Completed
Completed
100%
Causes
- Damaged/chafed wiring in the door harness (hinge/b-pillar area) shorted to battery feed
- Corroded or contaminated connector making unintended positive feed
- Failed door-ajar switch or lamp assembly with internal short to +
- Aftermarket equipment or alarm/comfort module wired incorrectly
- Water ingress causing conductive path to positive
- Faulty BCM or internal module driver (less common)
Symptoms
- Door open/ajar warning lamp or message illuminated continuously
- Interior courtesy lamps stay on or behave erratically
- Battery drain when vehicle is parked
- Vehicle may not lock/arm correctly or may display related messages
- DTC B1325 stored and may reappear after clearing
What to check
- Obtain stored codes and freeze frame data with a diagnostic scanner; note any related body/comfort codes
- Perform visual inspection of door harness, boot/hinge area and connectors for abrasion, corrosion or damage
- Verify the status of the door-ajar switch and associated lamp (operate door and watch for lamp/signal changes)
- Backprobe the door-ajar lamp/switch circuit at the BCM or connector and measure voltage with door open/closed
- Disconnect the door switch/lamp connector to see if the fault and symptom stop (isolates circuit from door wiring)
- Inspect for aftermarket wiring or modules tied into the circuit
Signal parameters
- Battery feed voltage (reference): 11–14.5 V (engine running or battery charged)
- Expected lamp/switch circuit when system indicates 'lamp off': near 0 V or high impedance to battery (no + present)
- Expected lamp/switch circuit when 'door open' is commanded: voltage state determined by design (typically pulled to ground or battery depending on vehicle); compare to manufacturer reference
- Measured fault condition: circuit shows battery voltage (~9–14 V) when it should be low/open
Diagnostic algorithm
- Read and record all stored codes and live data. Note which door(s) are reported open.
- Visually inspect the door wiring harness, especially at the hinge/boot area and connectors for damage, corrosion or water entry.
- Operate the door while backprobing the lamp/switch wire at the connector or BCM. Observe voltage with the door open and closed. A short to + will show battery voltage when the circuit should be low/open.
- Disconnect the door switch or remove the interior lamp connector. If the fault clears and symptoms stop, the issue is in the door/switch/connector wiring side.
- Isolate the circuit: remove connectors sequentially toward the BCM to locate the short. Use a multimeter to measure continuity to battery + with ignition off (verify fused feed first) and to ground where appropriate.
- Inspect and repair any chafed wires, damaged insulation, corroded terminals or water-damaged components. Repair using proper solder/crimp techniques and restore sealing on boots.
- If wiring and switch/lamp are good, consider replacing the door-ajar switch or lamp module. If problem persists after isolating wiring and components, consider BCM input/driver fault and consult manufacturer procedure before replacing.
- After repair, clear codes, exercise the doors and retest for intermittent faults. Verify no battery drain and correct lamp operation.
Likely causes
- Pinched or broken wires in the door hinge/boot area rubbing through to a positive conductor
- Connector corrosion at the door switch or lamp connector allowing battery voltage onto the signal
- Faulty door-ajar switch with internal short to battery
- Aftermarket accessory tied into the wrong circuit
Fault status
Status
Door open warning lamp circuit short to positive detected. Check door wiring, switch and connectors.
Repair difficulty: Medium
Diagnostic time: 0.5-2.5 hours
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