What Does B1331 Mean?
This code indicates the Body Control Module (BCM) has detected a malfunction in the decklid or rear door ajar switch circuit. The BCM is not receiving proper signals from the position sensor/switch that monitors whether the trunk lid or rear hatch is open or closed. This typically results in a persistent dashboard warning light and may prevent proper locking or alarm arming.
Common Causes
45%
Faulty or misaligned decklid/trunk latch switch or sensor
30%
Damaged, corroded, or disconnected wiring harness or connector at the decklid latch
15%
Worn or damaged decklid striker or latch mechanism causing improper closure detection
10%
Body Control Module (BCM) internal fault or software issue
Diagnostic Steps
1
Step 1: Perform visual inspection of decklid latch assembly and switch for physical damage, corrosion, or misalignment. Check that the striker properly engages the latch mechanism when closed.
2
Step 2: With ignition on, manually actuate the decklid latch switch while monitoring live data on scan tool to verify switch signal changes between open/closed states. Expected readings should toggle between 0V (closed) and 5V or 12V (open).
3
Step 3: Using a multimeter, check continuity and resistance of the decklid switch circuit from the latch connector back to the BCM connector. Test for short to ground, short to power, and open circuits. Compare readings to factory specifications (typically 0-5 ohms for continuity).
4
Step 4: Inspect connector terminals at both the latch and BCM for corrosion, bent pins, or moisture intrusion. Clean or repair as needed and apply dielectric grease.
5
Step 5: If all circuits test normal, substitute a known-good latch switch assembly or test with a signal simulator to isolate between switch and BCM failure.
6
Step 6: Clear codes, cycle the decklid multiple times, and verify repair by monitoring for code return and proper dashboard warning light operation.
Estimated Repair Cost
$75 - $450
Parts + labor, varies by vehicle and location
This code indicates the Body Control Module (BCM) has detected a malfunction in the decklid or rear door ajar switch circuit. The BCM is not receiving proper signals from the position sensor/switch that monitors whether the trunk lid or rear hatch is open or closed. This typically results in a persi...
The most common cause of B1331 (Decklid Ajar Rear Door Circuit Failure) is: Faulty or misaligned decklid/trunk latch switch or sensor
Typical repair costs for B1331 range from $75 to $450, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Safe to continue driving. This is primarily a convenience and security issue that may prevent proper vehicle locking, alarm arming, or cause unnecessary battery drain from interior lights. Repair at next convenient opportunity.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to B1331 to identify the root cause.
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Quick Info
Category
Body
System
Body Control and Security System
Difficulty
Type
Manufacturer
Recommended Tools
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