What Does B1564 Mean?
This code indicates the Body Control Module (BCM) has detected an open circuit in the door ajar switch or its wiring harness. The door ajar system monitors whether vehicle doors are properly closed and communicates this status to the BCM for interior lighting, security, and warning systems. An open circuit means the electrical pathway is interrupted, preventing the BCM from receiving proper door position signals.
Common Causes
45%
Faulty or corroded door ajar switch/sensor at the door latch assembly
30%
Broken, chafed, or damaged wiring harness between door jamb and BCM
15%
Loose or corroded electrical connector at door switch or BCM
10%
Failed Body Control Module (BCM) internal circuit
Diagnostic Steps
1
Step 1: Visually inspect all door ajar switches at each door latch assembly for physical damage, corrosion, or misalignment. Check for proper switch actuation when door is opened and closed.
2
Step 2: Using a digital multimeter, test continuity of the door ajar switch in both open and closed positions. Switch should show continuity (0-2 ohms) when door is open and infinite resistance when closed, or vice versa depending on manufacturer design.
3
Step 3: Inspect wiring harness from door jamb boot to BCM for chafing, breaks, or damage. Pay special attention to flex points where door opens and closes. Test continuity through entire harness with doors open and closed while flexing wires.
4
Step 4: Disconnect door ajar switch connector and inspect for corrosion, bent pins, or moisture intrusion. Clean connectors with electrical contact cleaner and dielectric grease if corrosion is present.
5
Step 5: With connector disconnected, measure voltage or ground signal at BCM side of circuit per manufacturer specifications (typically 5V reference or ground). This confirms BCM is providing proper signal to switch.
6
Step 6: After repairs, clear codes and cycle all doors multiple times while monitoring live data to confirm BCM properly receives door position signals and interior lights respond correctly.
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 door ajar switch or its wiring harness. The door ajar system monitors whether vehicle doors are properly closed and communicates this status to the BCM for interior lighting, security, and warning systems. An open ...
The most common cause of B1564 (Door Ajar Circuit Open) is: Faulty or corroded door ajar switch/sensor at the door latch assembly
Typical repair costs for B1564 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 code primarily affects interior lighting operation, dome light function, and door ajar warning indicators. May prevent vehicle from entering proper security mode or cause unnecessary battery drain if interior lights remain on.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to B1564 to identify the root cause.
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Quick Info
Category
Body
System
Body Control and Lighting System
Difficulty
Type
Manufacturer
Recommended Tools
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