Code
B1333
FIAT
B — Body
Tailgate open circuit
AI status
Completed
Completed
100%
Causes
- Damaged or disconnected wiring in tailgate harness
- Corroded or loose connector at tailgate latch or body harness
- Faulty tailgate latch switch or position sensor
- Failed or intermittent input on the body control module
- Blown fuse or poor ground related to the tailgate circuit
- Water intrusion or corrosion in tailgate area
Symptoms
- Tailgate open warning lamp or message in instrument cluster
- Interior or tailgate courtesy lights remain on or do not function correctly
- Remote locking/unlocking may not operate correctly for tailgate
- Central locking reports fault for tailgate only
- Audio/vehicle alerts for open tailgate
- Possible draining battery if lights stay on
What to check
- Connect diagnostic scan tool and read freeze frame data and live inputs for tailgate position
- Visually inspect tailgate latch, harness, and connectors for damage, corrosion, or water
- Check relevant fuses and grounds for continuity and condition
- Operate tailgate while watching live data to see signal change
- Wiggle test wiring at hinge and connector while monitoring input for intermittent changes
- Measure continuity/resistance between BCM connector and latch switch
Signal parameters
- Type: discrete switch input to BCM (normally open or closed depending on design)
- Expected idle levels: typical open-circuit = battery voltage via pull-up (~12 V), closed = near 0 V (ground) — confirm with vehicle wiring diagram
- Switch resistance: near 0 Ω when closed, open/infinite when open
- No-load continuity between latch switch terminals when actuated
Diagnostic algorithm
- Retrieve code(s) and any related body module codes with a scan tool. Clear codes and see if B1333 returns.
- Verify live data: monitor the tailgate position sensor input while manually opening/closing the tailgate. Note whether the input changes state.
- Inspect the tailgate latch, wiring harness through the hinge boot, and the connector for physical damage, corrosion, or contamination. Repair or clean as needed.
- Check fuses and ground points associated with the body control module/tailgate circuit; repair poor grounds or replace blown fuses.
- With ignition on, backprobe the latch switch connector and measure voltage. Compare to expected signal parameters. Perform continuity check to BCM input pin with connectors disconnected as required.
- If intermittent, perform a wiggle test along the harness while monitoring the signal to reproduce the fault. Pay special attention to the hinge area.
- If wiring and connectors are good but input remains incorrect, consider replacing the tailgate latch/sensor assembly.
- If new latch does not correct the issue, check BCM input circuit for open/short to supply or ground and consider module repair or replacement as a last resort.
- After repair, clear codes and verify proper operation through several open/close cycles and a road/usage test if applicable.
Likely causes
- Broken wires or chafing where wiring flexes at the tailgate hinge
- Contaminated/oxidised connector pins at latch or junction
- Mechanical failure of the latch switch (stuck or broken plunger)
- Intermittent BCM input due to internal failure or software glitch
Fault status
Status
Tailgate open circuit detected — open or intermittent circuit in tailgate latch/sensor wiring or connector. Inspect harness, connector and latch sensor; verify BCM input.
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
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