B1571 – Door Ajar LR Circuit Failure

The ODBII code B1571 Door Ajar LR Circuit Failure indicates a malfunction in the left rear door ajar switch circuit, suggesting that the vehicle’s system is detecting an issue with the door’s open/closed status.

The severity of ODBII code B1571 Door Ajar LR Circuit Failure is generally considered moderate.

Common Causes For: B1570 Lamp Headlamp High-Beam Circuit Short To Ground

• Faulty door ajar switch
• Damaged wiring or connectors
• Short circuit in the circuit
• Open circuit in the circuit
• Corroded terminals
• Malfunctioning body control module (BCM)
• Misaligned door or latch mechanism

Common misdiagnosis for B1571 Door Ajar LR Circuit Failure

• Faulty door latch assembly
• Malfunctioning door switch
• Wiring issues or shorts in the circuit
• Body control module (BCM) failure
• Incorrectly installed or damaged door seal
• Faulty ground connection
• Issues with the vehicle’s alarm system
• Problems with the instrument cluster or dashboard indicators

Common Troubleshooting Steps

The OBD-II code B1571 indicates a “Door Ajar” circuit failure, specifically for the left rear (LR) door. This code typically points to an issue with the door ajar switch or the wiring associated with that switch. Here are some common troubleshooting steps to diagnose and resolve the issue:

• Visual Inspection: **Check the Door Ajar Switch: Inspect the left rear door ajar switch for any visible damage or wear. Ensure that it is properly mounted and not stuck in the “open” position.
• **Wiring Inspection: Look for any damaged, frayed, or corroded wiring in the door harness. Pay special attention to the connectors and terminals.
• Test the Door Ajar Switch: **Multimeter Test: Use a multimeter to test the door ajar switch. With the door closed, the switch should show continuity (closed circuit). When the door is open, it should show no continuity (open circuit).
• **Manual Activation: Manually activate the switch (if possible) to see if it changes the status on the dashboard or triggers the warning light.
• Check for Faulty Connections: **Connector Inspection: Ensure that all connectors related to the door ajar switch are clean and securely connected. Look for any signs of corrosion or loose connections.
• **Ground Connections: Check the ground connections for the door ajar circuit to ensure they are secure and free of corrosion.
• Scan for Additional Codes: **Check for Other Codes: Use an OBD-II scanner to check for any additional trouble codes that may provide more context or indicate related issues.
• Inspect the Body Control Module (BCM): **BCM Functionality: The BCM often processes the signals from the door ajar switches. If other troubleshooting steps do not resolve the issue, consider checking the BCM for faults or software updates.
• Perform a System Reset: **Clear Codes: After performing any repairs or adjustments, clear the trouble codes using an OBD-II scanner and see if the code returns after a test drive.
• Consult Wiring Diagrams: **Refer to Service Manual: If the issue persists, consult the vehicle’s service manual for wiring diagrams and specific troubleshooting procedures related to the door ajar circuit.
• Professional Diagnosis: **Seek Help if Needed: If you are unable to resolve the issue after these steps, consider seeking assistance from a professional mechanic or automotive technician who can perform more advanced diagnostics. By following these steps, you should be able to identify and resolve the issue related to the B1571 code.