Code
B1333
ALFA ROMEO
B — Body
Tailgate open circuit
Views:
UK: 22
EN: 35
RU: 21
AI status
Completed
Completed
100%
Causes
- Broken or disconnected wiring in the tailgate harness (common at hinge area)
- Corroded or loose connector at the tailgate latch or body control module (BCM)
- Failed tailgate latch switch or integrated position sensor
- Poor ground or power supply to the latch/sensor circuit
- Water ingress or corrosion inside the latch or connector
- Faulty BCM or software/firmware communication error
Symptoms
- Tailgate open warning lamp/messages illuminated while tailgate is closed
- Interior trunk/tailgate light remains ON
- Central locking does not lock/unlock tailgate
- Alarm may not arm or may give false alarms
- Battery drain when vehicle is parked
- Inability to detect tailgate closed for vehicle systems (e.g., auto-lock)
What to check
- Read stored fault codes and freeze-frame with a diagnostic tool; record any related B-codes
- Visually inspect tailgate latch, harness, and connectors for damage, corrosion, or intrusion
- Operate tailgate while observing connector/harness for pinching or broken wires (wiggle test)
- Check relevant fuses and relays supplying the tailgate circuit
- Perform continuity test of the latch switch circuit from latch to BCM connector
- Measure supply voltage and ground at the latch connector with tailgate open and closed
Signal parameters
- Typical latch switch: closed = continuity (near 0 Ω) between switch terminals; open = OL / infinite Ω
- Voltage-type sensors: closed/secure = approx. 0 V or chassis ground (if switch to ground), open = approx. 12 V (pulled up by BCM) — verify with service manual
- Signal toggles when tailgate is opened/closed; steady invalid/unavailable signal indicates open circuit
- No communication packets from a dedicated tailgate control module may indicate module or CAN wiring issue
Diagnostic algorithm
- Connect a diagnostic scanner and confirm B1333 and any related codes. Note whether the code is permanent, stored, or intermittent.
- Ask the owner for symptom details (when it occurs, after rain, after door closing). Try to reproduce the fault.
- Visually inspect the tailgate seal area, latch and harness routing through the hinge boot. Look for chafing, broken wires, corrosion or water entry.
- With ignition ON, backprobe the tailgate latch connector. Observe signal voltage/continuity while operating the latch (open/close). Compare to expected values in signal_params.
- If no signal or intermittent, perform continuity/resistance check from latch connector to the BCM connector to locate open circuit or high resistance. Pay attention to the hinge area where wires flex.
- Inspect and clean connectors; reseat or replace corroded terminals. Repair or splice damaged wires using correct automotive techniques and strain relief in the hinge area.
- If wiring and switch test good, verify power/ground at the BCM for the circuit. Check BCM grounds and supply fuses/relays.
- If wiring, switch, power and ground are correct but fault persists, investigate BCM input circuit or tailgate control module (if separate). Check for software updates or resets from OEM literature before replacement.
- After repairs, clear codes and perform several open/close cycles and road test to confirm the fault is resolved and no new codes are stored.
Likely causes
- Damaged wiring at the tailgate hinge causing intermittent open circuit
- Failed or stuck tailgate latch sensor
- Corroded connector at tailgate latch
- Poor ground at tailgate or BCM
- Connector pin pushed out or broken
Fault status
Status
Tailgate open circuit detected — the latch/position sensor signal is absent or open. This may prevent correct detection of a closed tailgate and can cause warning messages, lighting or locking faults.
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
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