B1337: RR Door Ajar Switch Short to Battery
The B1337 code indicates that the Body Control Module (BCM/GEM) has detected a short to battery voltage (B+) on the right rear door ajar switch signal circuit. This circuit normally reads ground when the door is open; the presence of battery voltage prevents the BCM from correctly detecting the door's status, affecting interior lighting, central locking, and the alarm system.
1. Commonly Affected Makes
2. Most Common Causes
- Right rear door ajar switch internally shorted to battery voltage
- Signal circuit wire (typically gray/black or similar per diagram) chafed or pinched against a B+ wire
- Damaged, corroded, or bridged terminals at the switch or BCM connector
- Internal failure of the input driver in the BCM/GEM module
3. Symptoms You Will Notice
- Interior lights stay on or behave erratically
- Door ajar warning light or chime active with the door closed
- Central locking system may not lock/unlock properly
- Alarm system may false trigger or fail to arm
4. Step-by-Step Diagnosis
Scan for B1337 and note any related codes
Visually inspect the right rear door ajar switch and its wiring harness for damage, chafing, or corrosion
Disconnect the switch and measure voltage on the signal wire at the BCM; should be near 0V with switch open; if B+ is present, trace the short
Check for continuity between the signal wire and ground when the switch is pressed; if not, replace the switch
If wiring and switch check out, suspect a faulty BCM and perform a module test or replacement
5. Frequently Asked Questions
Is it safe to drive?▼
Yes, the vehicle is generally safe to drive, but you may experience electrical issues such as interior lights staying on (which can drain the battery) or alarm malfunctions. It's recommended to diagnose and repair the issue promptly.
How much does it cost to fix?▼
The cost varies depending on the cause. A switch replacement typically ranges from $50 to $150 including parts and labor. Wiring repairs can cost $100 to $300. If the BCM needs replacement, expect $400 to $800 or more.