Code
B1325
FIAT
B — Body
Door open warning lamp circuit short to positive
Views:
UK: 7
EN: 9
RU: 7
AI status
Completed
Completed
100%
Causes
- Damaged wiring harness with insulation abrasion contacting +12V
- Faulty or stuck door switch feeding battery voltage into the circuit
- Shorted connector pin at lamp, switch or BCM to a fused +12V feed
- Corroded or water-damaged connector allowing unintended contact with power
- Faulty instrument cluster/BCM internal driver
- Aftermarket accessory or alarm improperly tied into door circuit
Symptoms
- Door-open warning lamp permanently on or intermittently illuminated
- Door-open indicator shows open when door is closed
- Incorrect chime/indicator behavior for door ajar
- Battery drain when vehicle is parked (lamp stays on)
- Related door/lock central functions may behave erratically
What to check
- Scan vehicle with a capable diagnostic tool; read and record B1325 and any related codes, freeze frame and live data
- Visually inspect wiring and connectors from door jamb harness to door switch, lamp cluster and BCM for damage, corrosion, water ingress, melted insulation or aftermarket splices
- With ignition ON, measure voltage at the lamp/switch connector and at BCM input pin using a digital multimeter
- Operate the door switch while monitoring voltage to confirm change of state and to see if 12 V is present when circuit should be open
- Perform a wiggle test on harnesses and connectors while watching live data or DMM for intermittent contact
- Disconnect the door lamp/cluster and/or door switch connector to see if the code clears or lamp goes out (helps isolate circuit section)
Signal parameters
- Closed circuit (door open) expected: ~12 V at lamp side (battery voltage) or switch input depending on design
- Open circuit (door closed) expected: ~0 V or high impedance at the BCM/switch input (no battery voltage present)
- Short to positive condition: ~12 V present at BCM input when door closed (should be low)
- Typical lamp circuit current: small diagnostic/indicator currents (mA range) for lamp feed; full lamp current only when lamp illuminated — compare to service spec if available
Diagnostic algorithm
- Connect a scan tool; record DTC and any related codes and live data for door-open inputs.
- Perform visual inspection of door jamb wiring, harness grommet and connectors for physical damage, corrosion or missing insulation.
- With ignition ON, backprobe the door lamp/switch circuit at the body side connector. Verify voltage with door closed and open; note unexpected 12 V when closed.
- Disconnect the door switch/door lamp connector: if the fault disappears, suspect switch, connector or door harness segment. If fault remains, suspect BCM or wiring upstream.
- Isolate the short by disconnecting harness sections (door harness, A-pillar, under-dash) and observing when the circuit returns to normal; use continuity/ohmmeter to check for unintended continuity to battery positive.
- Inspect and test the door switch: measure resistance or switch operation; replace if contacts are shorted/welded.
- Inspect connectors for pin damage and for pins pushed into adjacent circuits; repair or replace connectors and repair wiring with OEM repair methods (solder and heat-shrink or approved crimps).
- If wiring and switch check good, test by disconnecting BCM input; if short remains to vehicle +12V at BCM pin, replace or repair BCM as per service manual.
- After repair, clear codes and perform functional test cycles (open/close doors, verify lamp and chime behavior) and road-test to confirm repair.
- Advise final corrosion protection, secure harness routing and re-check for any aftermarket device connections that may have caused the fault.
Likely causes
- Pin chafing at door hinge/door harness bundle contacting constant hot feed
- Door switch plunger stuck or switch contacts welded closed to +12V
- Lamp/cluster connector pin pushed into adjacent +12V terminal
- BCM input transistor failed shorted to battery rail
- Previous repair or splice incorrectly connected to a constant 12 V source
Fault status
Status
B1325 — Door open warning lamp circuit short to positive (unexpected battery voltage on lamp/switch circuit)
Repair difficulty: Medium
Diagnostic time: 0.5 - 1.5 hours
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