Code
B1338
FIAT
B — Body
Right rear door open circuit short to ground
Views:
UK: 2
EN: 5
RU: 3
AI status
Completed
Completed
100%
Causes
- Wiring insulation damaged in right rear door harness (pinch at hinge/rubber boot)
- Connector corrosion or water ingress at door/jamb connector
- Damaged or shorted door latch/switch assembly
- Aftermarket alarm/lighting wiring tied into the door circuit and shorted to ground
- Broken or bent connector pins causing contact with ground
- Intermittent/failed body control module (BCM) input (less common)
Symptoms
- Right rear door ajar/door open indicator illuminated or stuck
- Interior lights or courtesy lamp remaining on for that door
- Central locking or remote lock/unlock not operating correctly for right rear door
- Possible parasitic battery drain when vehicle is off
- Stored DTC B1338 and possibly related BCM door circuit faults
What to check
- Read and record stored codes and freeze-frame data with a scan tool; clear and re-scan after tests
- Visual inspection of right rear door wiring, rubber boot, and connectors for chafing, breaks, corrosion or water ingress
- Inspect and wiggle the harness at the door hinge while monitoring the door status on a scan tool to reproduce the fault
- Disconnect the right rear door connector and check for continuity between the signal pin and chassis ground
- Check for aftermarket devices spliced into the door circuit
- Inspect BCM connector for bent pins or corrosion
Signal parameters
- Expected signal behavior: input should change state when door opens/closes (either pull-to-ground or pull-to-battery design depending on vehicle). Fault: input remains grounded (near 0 V) regardless of door position.
- Typical battery voltage reference: ~12–14 V (use as reference for powered state checks).
- Fault reading: signal wire to chassis ground = ~0 Ω–
- Normal open-circuit reading: signal to ground >10 kΩ or open (shows no direct continuity) depending on design.
Diagnostic algorithm
- Use a scan tool to confirm B1338 and note any related BCM or door circuit codes. Record door status live data.
- Visually inspect the right rear door latch, switch, harness, and rubber boot for damage, corrosion, or water. Check for aftermarket splices.
- With ignition off, disconnect the right rear door electrical connector at the door jamb. Using a multimeter, measure resistance between the door signal pin and chassis ground. If near 0 Ω, there is a short to ground in the door side wiring/switch.
- With connector disconnected, inspect continuity from the harness side (vehicle body) back to the BCM connector to isolate whether the short is in the door harness or the body harness/BCM. If the harness side is open to ground, fault is in door wiring/switch.
- If the short is on the door side, open the door panel and inspect/repair wiring through the hinge boot; look for pinched or broken conductors where harness flexes. Repair/replace damaged sections and protect with new boot and loom.
- If the short appears on the body harness or at BCM connector, inspect the connector pins and wiring for corrosion/shorts. Repair splices or damaged wire; replace connector if necessary.
- After repairs, reconnect connectors, clear codes, and cycle door open/close while monitoring the door input with a scan tool to confirm the fault is resolved. Check for parasitic drain if interior lamp behavior was affected.
- If wiring and connectors are good and the input still reads grounded, consider replacing the door latch/switch assembly. Only after exhausting wiring and switch checks, suspect BCM input failure and consult manufacturer procedures before replacing the module.
Likely causes
- Shorted signal wire to chassis ground inside door boot where harness flexes
- Corroded terminals at the right rear door connector allowing continuity to ground
- Door latch/switch internal failure allowing constant ground
- Water intrusion in door cavity creating a conductive path to ground
Fault status
Status
Right rear door switch circuit — short to ground detected on BCM input. Door input held low.
Repair difficulty: Medium
Diagnostic time: 1.0-2.5 hours
Similar codes
Your experience will help others
+100 karma for a short comment :)
Was this AI description helpful?
Your feedback helps improve AI descriptions.
👍 Like
0
👎 Dislike
0
Send to email