What Does B1329 Mean?
This diagnostic trouble code indicates that the Body Control Module (BCM) has detected a short to battery voltage in the passenger door ajar switch circuit. The circuit is reading constant battery voltage (typically 12+ volts) when it should be reading ground or a lower reference voltage, causing the system to believe the door is continuously ajar or experiencing an electrical fault. This condition prevents the BCM from accurately monitoring the passenger door position status.
Common Causes
45%
Damaged or chafed wiring in the door harness causing a short to battery voltage, typically in the door jamb area where flexing occurs
30%
Faulty passenger door ajar switch with internal short to power supply
15%
Water intrusion or corrosion in door ajar switch connector causing cross-circuit short
10%
BCM internal fault or damaged BCM connector terminal creating false short detection
Diagnostic Steps
1
Step 1: Perform visual inspection of passenger door ajar switch and connector for obvious damage, corrosion, or water intrusion. Check for pushed-out terminals or damaged connector seals.
2
Step 2: With ignition off, disconnect the passenger door ajar switch connector and use a digital multimeter to measure voltage at the BCM side of the harness connector. Should read 0 volts with switch disconnected; battery voltage indicates wiring short.
3
Step 3: Inspect door harness in the door jamb area by flexing wires while monitoring voltage. Look for chafed insulation or pinched wires that may contact power circuits. Pay special attention to areas where harness bends during door operation.
4
Step 4: If wiring tests normal, check door ajar switch resistance with ohmmeter. With door open, resistance should be within specification (typically 0-5 ohms to ground); with door closed, open circuit or high resistance (typically >10K ohms). Replace switch if out of specification.
5
Step 5: If all components test normal, suspect BCM internal fault. Test BCM connector terminals for damage, corrosion, or poor contact. Verify BCM ground circuits are intact.
6
Step 6: Clear codes, operate door through multiple open/close cycles, and verify repair by confirming code does not return and door ajar indicator functions properly on instrument cluster.
Estimated Repair Cost
$75 - $450
Parts + labor, varies by vehicle and location
This diagnostic trouble code indicates that the Body Control Module (BCM) has detected a short to battery voltage in the passenger door ajar switch circuit. The circuit is reading constant battery voltage (typically 12+ volts) when it should be reading ground or a lower reference voltage, causing th...
The most common cause of B1329 (Passenger Door Ajar Circuit Short To Battery) is: Damaged or chafed wiring in the door harness causing a short to battery voltage, typically in the door jamb area where flexing occurs
Typical repair costs for B1329 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 as this is a monitoring circuit fault only. However, interior lights may stay on continuously draining the battery, and security systems may not arm properly if vehicle thinks door is open.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to B1329 to identify the root cause.
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Quick Info
Category
Body
System
Body Control and Door Monitoring System
Difficulty
Type
Manufacturer
Recommended Tools
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