B1338 — Door Ajar RR Circuit Short To Ground #

Please note: The code B1338 — Door Ajar RR Circuit Short To Ground may have different wording depending on the vehicle manufacturer. Always refer to your OEM (Original Equipment Manufacturer) service manual for precise terminology.

• Door Ajar RR Circuit Short To Ground (Generic)
• Right Rear Door Ajar Switch Circuit Shorted to Ground (Ford, Lincoln, Mercury)
• RR Door Ajar Switch Short/Ground Fault (GM, Chevrolet, GMC)
• Rear Right Door Open Sensor Circuit Low (Toyota, Lexus)
• Right Rear Door Ajar Input Low (Chrysler, Dodge, Jeep)

Summary of DTC B1338 #

DTC B1338 indicates that the vehicle’s computer has detected an electrical short to ground in the right rear (RR) door ajar circuit. This circuit monitors whether the rear right door is properly closed or not, using a door-ajar switch or sensor. When the circuit is shorted to ground, the system may falsely report the door as open, even if it’s securely shut. This can trigger warning lights, interior lights, or security system malfunctions. The code is common across various car brands and is part of the OBD-II/EOBD body codes, primarily affecting the convenience and security features of your vehicle.

Frequent Symptoms for DTC B1338 #

When the B1338 code appears, you may notice several unusual behaviors related to the right rear door’s status. These symptoms are mostly annoying but can also impact vehicle security and comfort. Typical driver complaints include:

• Warning light for “door open” remains illuminated, even when all doors are closed
• Interior dome lights stay on or turn on intermittently while driving
• Chimes or audible alerts about the rear right door being open
• Security system fails to arm or triggers false alarms
• Automatic door locking/unlocking malfunctions
• Window or child safety lock issues on the right rear door

Probable Causes for DTC B1338 #

The root cause of a B1338 fault is always an unwanted connection between the door-ajar sensor circuit and the vehicle’s chassis ground. However, several underlying issues may be responsible, ranked here from most to least common:

1. Damaged or pinched wiring harness in the right rear door area
2. Faulty or contaminated right rear door-ajar switch (also called door open sensor)
3. Corroded or loose electrical connectors at the door, B-pillar, or under the seat
4. Water intrusion causing short circuits inside the door or at connectors
5. Incorrectly installed aftermarket equipment (such as alarms or remote starters)
6. Defective Body Control Module (BCM) — rare, but possible

Step-by-Step Diagnostic Guide for B1338 #

Fixing B1338 starts with a careful inspection and methodical troubleshooting. Here’s a proven step-by-step approach for DIYers and pros alike:

• Scan for codes: Use an OBD-II scanner to confirm B1338 and check for related codes.
• Visual inspection: Examine the right rear door wiring harness, especially where it passes through the door jamb (flexing area).
• Check the door-ajar switch: Remove the right rear door panel and locate the switch. Look for dirt, corrosion, or damage.
• Test for continuity: With a multimeter, check the circuit between the switch and ground. If there’s zero resistance, a short is present.
• Inspect connectors: Unplug and examine all connectors between the door and the main body wiring; look for bent pins or moisture.
• Simulate open/closed door: Manually operate the switch and observe the code status or warning lights.
• Check for water or aftermarket equipment: Look for signs of recent water entry or non-OEM wiring.
• If all else fails: Test the circuit at the Body Control Module (BCM) and consult wiring diagrams.

Possible Repairs for B1338 #

Once you’ve pinpointed the cause, apply the appropriate repair to clear the B1338 code. Common fixes include:

• Repair or replace damaged wiring in the right rear door harness
• Replace the right rear door-ajar switch if faulty or stuck
• Clean and reseat corroded connectors in the door and B-pillar area
• Address water leaks by sealing door gaskets or drain holes
• Remove or correct aftermarket wiring causing interference
• Replace the Body Control Module (BCM) only after confirming all wiring and switch integrity

Is it Safe to Drive with B1338? #

Yes, you can typically drive with code B1338 present, as it does not directly impact the engine, brakes, or other critical safety systems. However, living with this code may mean your interior lights stay on, battery drain risk increases, or your alarm system malfunctions. For security and comfort, and to avoid further electrical issues, it’s best to resolve the cause promptly.

Vehicles Most Commonly Affected by B1338 #

While the B1338 code can appear on any OBD-II equipped vehicle, it’s most frequently reported on certain makes and models, especially those with advanced body electronics. Notably:

• Ford (Fusion, Escape, F-150, Explorer, Taurus)
• Lincoln (MKZ, Navigator, MKX)
• GM/Chevrolet (Silverado, Tahoe, Suburban, Malibu)
• Toyota (Camry, Highlander, Corolla)
• Chrysler/Dodge/Jeep (Grand Cherokee, Durango, 300)

Common Mistakes & Best Practices for B1338 #

Technicians and DIYers sometimes overlook simple issues or misdiagnose the problem. Don’t fall into these traps—follow these best practices:

• Don’t immediately replace the switch without checking for wiring or connector issues first
• Always inspect the harness in flexing areas (door jambs), as wires often break inside the insulation
• Thoroughly dry and clean connectors before reassembly if water intrusion is suspected
• Don’t ignore related codes that may indicate a broader electrical issue
• Document what you check—it saves time if the problem recurs

Quick FAQ on DTC B1338 #

Here are some concise answers to common questions about B1338:

• Q: Will this code drain my battery?
  A: If your interior lights stay on due to the code, there is a risk of battery drain. Repair promptly to avoid a dead battery.
• Q: Can I fix this myself?
  A: If you’re comfortable removing door panels and using a multimeter, many causes—like bad switches or visible wiring damage—can be handled DIY. For complicated wiring or BCM faults, professional help is recommended.
• Q: Does this affect power windows or door locks?
  A: Sometimes. If the Body Control Module interprets the door as open, it may disable auto-locking or window controls for that door as a safety feature.