B1337 — Door Ajar RR Circuit Short To Battery #

Note: The description for DTC B1337 may vary between vehicle manufacturers.

• Ford: Door Ajar RR Circuit Short To Battery
• Lincoln: Door Ajar RR Circuit Short To Battery
• Mercury: Door Ajar RR Circuit Short To Battery
• General variation: Right Rear Door Ajar Circuit Shorted to Battery

Summary of DTC B1337 #

DTC B1337 indicates that the vehicle’s control module has detected a short to battery voltage (short to power) within the right rear (RR) door ajar circuit. In simple terms, the system senses voltage where it shouldn’t be, suggesting an electrical fault. The “door ajar” switch is responsible for telling the vehicle’s computer whether a door is open or closed. When the right rear door circuit is compromised, it can cause false alerts or prevent proper operation of related features, such as interior lights or security systems. This code is primarily seen on Ford, Lincoln, and Mercury vehicles but can appear on others with similar circuitry.

Frequent Symptoms for Code B1337 #

When B1337 is present, you may notice odd electrical behavior tied to the right rear door. The symptoms often appear as inconveniences, but they can also affect vehicle security and comfort functions. Here’s what you might experience:

• “Door Ajar” warning light remains on, even when all doors are closed
• Interior lights stay on after closing the doors
• Right rear door not registering as closed (or open) in the vehicle computer
• Alarm or security system false triggers
• Remote locking/unlocking issues
• Battery drain (due to lights or modules staying active)

Probable Causes for Code B1337 #

The most common reasons for this code revolve around wiring and sensor issues. The fault means battery voltage is detected where only a low signal or ground should be present. Here are the likely culprits, ranked by frequency:

1. Damaged or chafed wiring in the right rear door harness (exposed to door movement)
2. Shorted door ajar switch (integrated into the door latch assembly)
3. Corroded or water-intruded connectors at the right rear door
4. Pinched harness after door repairs or window regulator work
5. Faulty or contaminated door latch mechanism
6. Less often: Fault in the Body Control Module (BCM), also called Smart Junction Box by some OEMs

Step-by-Step Diagnosis for Code B1337 #

Diagnosing B1337 is a matter of tracing the electrical path from the control module to the right rear door ajar switch. Here’s a proven approach:

• Verify the code with a proper OBD-II/EOBD scan tool and note freeze frame data
• Clear the code and observe if it returns immediately or after a specific door operation
• Inspect the right rear door latch and ajar switch for visible damage or contamination
• Check the door wiring harness for pinched, cut, or frayed wires—especially where the harness flexes at the door jamb
• Disconnect the harness connector at the door and check for corrosion, bent pins, or water intrusion
• Using a multimeter, check for unexpected battery voltage on the switch signal wire with the door closed
• If the wiring and switch seem intact, check continuity and resistance between the switch and BCM
• For rare cases, consult the OEM wiring diagram and test the BCM input/output

Possible Repairs for Code B1337 #

The repair depends on what you find during diagnosis. Most repairs are straightforward but may require parts replacement or minor wiring work. Here are the common fixes:

• Repair or replace damaged or shorted wires in the right rear door harness
• Replace the right rear door ajar switch (often part of the latch)
• Clean and secure any corroded connectors or terminals
• Realign or secure wiring to avoid future pinching or wear
• Replace the door latch assembly if the switch is internal and non-serviceable
• On rare occasions: Reprogram or replace the BCM if verified faulty

Can You Drive with Code B1337? #

Yes, but with limitations. B1337 is not a direct safety concern for driving, but it can cause irritating electrical issues and even lead to battery drain if interior lights stay on. More importantly, if your security system depends on the door ajar circuit, it may be compromised. For peace of mind and to avoid dead batteries or false alarms, plan to address the issue soon.

Vehicles Most Commonly Affected by B1337 #

This code is most frequently seen in certain Ford, Lincoln, and Mercury models from the late 1990s through the 2010s, which use similar door ajar and body control circuits. Some examples include:

• Ford Explorer
• Ford Expedition
• Ford F-150 and Super Duty trucks
• Ford Taurus
• Lincoln Navigator
• Mercury Mountaineer

Common Mistakes & Best Practices for Code B1337 #

Diagnosing body electrical codes can be tricky. Avoid these pitfalls, and follow these tips for a smooth repair:

• Mistake: Replacing the door latch or switch without checking the wiring—wiring faults are more common.
• Mistake: Overlooking hidden corrosion in connectors, especially after water leaks.
• Best practice: Carefully inspect the wire harness where it flexes at the door hinge—this is a prime failure spot.
• Best practice: Always clear the code and recheck after a repair to confirm the fix.
• Best practice: Use the OEM wiring diagram when in doubt, especially if the issue is intermittent.

Express FAQ for B1337 #

Here are quick answers to common questions about DTC B1337.

• Q: Can a faulty door ajar switch trigger the alarm randomly?
  A: Yes. If the switch or wiring is shorted, the security system may think the door is open or being tampered with, causing false alarms.
• Q: Will disconnecting the battery clear the B1337 code?
  A: Temporarily, but the code will return if the underlying issue isn’t fixed. Use a scan tool to clear the code after repairs.