WOMS
U code network High severity

U013B Lost Communication with Body Control Module (BCM) 'A'

The OBD2 code U013B indicates that there is a loss of communication between the vehicle's control module and the Body Control Module (BCM) 'A', which can affect various electrical systems and functions

Definition

The OBD2 code U013B indicates that there is a loss of communication between the vehicle's control module and the Body Control Module (BCM) 'A', which can affect various electrical systems and functions

Common causes

  • Faulty Body Control Module (BCM)
  • Damaged wiring or connectors
  • Corroded terminals
  • Poor ground connection
  • Faulty communication network (CAN bus)
  • Blown fuses
  • Software issues or programming errors
  • Intermittent electrical connections

Common misdiagnoses

  • Faulty Body Control Module (BCM)
  • Wiring issues or shorts in the communication lines
  • Faulty or corroded connectors
  • Issues with the Powertrain Control Module (PCM)
  • Malfunctioning Instrument Cluster
  • Battery or charging system problems
  • Faulty fuses related to the BCM
  • Software or firmware issues in the BCM or other modules
  • Grounding issues in the electrical system
  • Other communication network failures (e.g., CAN bus issues)

Troubleshooting steps

  1. 1. Check for Additional Codes

    Use an OBD-II scanner to check for any other trouble codes that may be present. This can provide more context and help identify related issues

  2. 2. Inspect Wiring and Connectors

    Visual Inspection: Check the wiring harness and connectors related to the Body Control Module (BCM) for any signs of damage, corrosion, or loose connections

  3. 3. Connector Pins

    Ensure that the pins in the connectors are not bent, corroded, or pushed back

  4. 4. Test the BCM

    Power and Ground: Verify that the BCM is receiving the correct power and ground signals. Use a multimeter to check voltage at the BCM connector

  5. 5. Communication Lines

    Check the communication lines (CAN bus) for continuity and proper voltage levels. Look for shorts or open circuits

  6. 6. Inspect Related Modules

    Since the BCM communicates with other modules, check for communication issues with other modules in the network. If other modules are also reporting communication errors, it may indicate a broader network issue

  7. 7. Check for Software Updates

    Verify if there are any software updates available for the BCM or other related modules. Sometimes, manufacturers release updates to fix communication issues

  8. 8. Perform a Hard Reset

    Disconnect the vehicle's battery for a few minutes to reset the BCM and other modules. Reconnect and see if the code reappears

  9. 9. Scan for Communication Issues

    Use a professional scan tool to monitor live data and check for communication between the BCM and other modules. This can help identify if the BCM is functioning correctly

  10. 10. Inspect Fuses

    Check the fuses related to the BCM and other modules. A blown fuse can interrupt communication

  11. 11. Check for Environmental Factors

    Look for any environmental factors that may affect the BCM, such as water intrusion or extreme temperatures

  12. 12. Replace the BCM (if necessary)

    If all other troubleshooting steps fail and the BCM is determined to be faulty, consider replacing it. Ensure that the new BCM is programmed and configured correctly for your vehicle.1

  13. 13. Consult Technical Service Bulletins (TSBs)

    Check for any TSBs related to the U013B code for your specific vehicle make and model. Manufacturers may have specific recommendations or known issues.1

  14. 14. Seek Professional Help

    If you are unable to resolve the issue, consider seeking help from a qualified automotive technician or dealership, especially if specialized diagnostic equipment is needed. By following these steps, you should be able to identify the root cause of the U013B code and take appropriate action to resolve the communication issue with the Body Control Module