What Does B1320 Mean?
This code indicates the Body Control Module (BCM) has detected an open circuit in the driver door ajar switch monitoring system. The BCM expects to see a specific voltage or resistance when the door is closed, but is instead seeing an open or high-resistance condition that prevents proper door status detection. This affects interior lighting, security systems, and warning indicators that rely on door position information.
Common Causes
40%
Faulty or misaligned driver door ajar switch/latch assembly with worn contacts or broken internal spring
30%
Broken, chafed, or corroded wiring in door jamb harness due to repeated flexing during door operation
20%
Corroded or loose electrical connector at door ajar switch or BCM connection point
10%
Failed Body Control Module (BCM) with internal circuit fault on door switch monitoring circuit
Diagnostic Steps
1
Step 1: Visually inspect the driver door ajar switch in the door latch/striker area for physical damage, corrosion, misalignment, or debris preventing proper operation. Manually actuate the switch if accessible and listen for clicking
2
Step 2: Using a digital multimeter, backprobe the door ajar switch connector and check for proper resistance/voltage change when manually operating the door latch between open and closed positions (typical values: closed = 0-5 ohms or 0V, open = infinite resistance or battery voltage depending on switch type)
3
Step 3: Inspect wiring harness in the door jamb area for chafing, broken wires, or damaged insulation by flexing the harness while monitoring circuit continuity with a multimeter. Pay special attention to the rubber boot where wiring passes between door and body
4
Step 4: Check connector terminals at both the door ajar switch and BCM for corrosion, bent pins, or poor contact. Clean with electrical contact cleaner and verify proper terminal tension. Measure resistance of entire circuit from BCM connector to switch (should be less than 5 ohms)
5
Step 5: After repairs, clear codes and cycle the driver door multiple times while monitoring live data on scan tool to confirm BCM now correctly detects door open/closed status without the circuit open fault returning
Estimated Repair Cost
$75 - $400
Parts + labor, varies by vehicle and location
This code indicates the Body Control Module (BCM) has detected an open circuit in the driver door ajar switch monitoring system. The BCM expects to see a specific voltage or resistance when the door is closed, but is instead seeing an open or high-resistance condition that prevents proper door statu...
The most common cause of B1320 (Driver Door Ajar Circuit Open) is: Faulty or misaligned driver door ajar switch/latch assembly with worn contacts or broken internal spring
Typical repair costs for B1320 range from $75 to $400, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Safe to continue driving. This primarily affects convenience features like interior lights, door ajar warnings, and may prevent proper vehicle security arming. Repair at your convenience to restore proper door status monitoring.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to B1320 to identify the root cause.
OBDHut Mobile App
Scan codes directly from your car with the OBDHut app.
Coming Soon
Quick Info
Category
Body
System
Body Control and Convenience Systems
Difficulty
Type
Manufacturer
Recommended Tools
OBD2 Scanner
A quality scan tool helps you read codes, view live data, and clear faults.
