B1311 – Power Door Unlock Circuit Open

The ODBII code B1311 indicates that there is an open circuit in the power door unlock system, meaning the system is not receiving the necessary electrical signal to operate the door unlock function.

The severity of ODBII code B1311 is generally considered moderate.

Common Causes For: B1310 Power Door Unlock Circuit Failure

• Faulty door lock actuator
• Damaged wiring or connectors
• Blown fuse
• Malfunctioning body control module (BCM)
• Faulty door switch
• Poor ground connection

Common misdiagnosis for B1311 Power Door Unlock Circuit Open

• Faulty door lock actuator
• Wiring issues or shorts in the door harness
• Malfunctioning body control module (BCM)
• Defective power door lock switch
• Issues with the vehicle’s central locking system
• Low battery voltage or poor battery connections
• Faulty relay or fuse related to the door lock system

Common Troubleshooting Steps

The OBD-II code B1311 indicates a problem with the power door unlock circuit, specifically that the circuit is open. This can be caused by various issues, including wiring problems, faulty components, or issues with the vehicle’s body control module (BCM). Here are some common troubleshooting steps to diagnose and resolve the B1311 code:

• Visual Inspection: **Wiring and Connectors: Check the wiring and connectors related to the power door unlock circuit for any signs of damage, corrosion, or loose connections.
• **Fuses: Inspect the fuses related to the door locks and BCM. Replace any blown fuses.
• Check the Door Lock Switch: **Functionality: Test the door lock switch to ensure it is functioning properly. You can use a multimeter to check for continuity when the switch is activated.
• **Wiring: Inspect the wiring from the switch to the BCM for any breaks or shorts.
• Test the Door Lock Actuator: **Operation: Manually test the door lock actuator to see if it operates correctly. You can apply direct power to the actuator to check if it unlocks the door.
• **Resistance Check: Use a multimeter to check the resistance of the actuator. If it is outside the manufacturer’s specifications, it may need to be replaced.
• Check the Body Control Module (BCM): **Connections: Ensure that the BCM connectors are secure and free of corrosion.
• **Functionality: If other components controlled by the BCM are also malfunctioning, the BCM itself may be faulty. You may need to perform a diagnostic test on the BCM.
• Scan for Additional Codes: Use an OBD-II scanner to check for any additional trouble codes that may provide more context or indicate related issues.
• Perform a Circuit Test: **Voltage and Ground: Use a multimeter to check for proper voltage and ground at the door lock actuator and switch. Ensure that the circuit is receiving power when the switch is activated.
• **Continuity Test: Perform a continuity test on the wiring harness to ensure there are no breaks in the circuit.
• Repair or Replace Components: Based on your findings, repair any damaged wiring or connectors. Replace any faulty switches, actuators, or the BCM if necessary.
• Clear the Code and Test Drive: After making repairs, clear the trouble code using an OBD-II scanner and take the vehicle for a test drive to see if the code returns.
• Consult Repair Manual: If the issue persists, consult the vehicle’s repair manual for specific troubleshooting steps and wiring diagrams related to the power door unlock circuit.
• Seek Professional Help: If you are unable to diagnose or fix the issue, consider seeking help from a professional mechanic or automotive technician. By following these steps, you should be able to identify and resolve the issue causing the B1311 code.