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U0140 Lost Communication With Body Control Module

The OBD2 code U0140 indicates that there is a loss of communication between the vehicle's control module and the body control module, which can affect various electrical systems and functions in the vehicle

Definition

The OBD2 code U0140 indicates that there is a loss of communication between the vehicle's control module and the body control module, which can affect various electrical systems and functions in the vehicle

Common causes

  • Faulty Body Control Module (BCM)
  • Damaged wiring or connectors
  • Corroded terminals
  • Blown fuses
  • Faulty communication network (CAN bus issues)
  • Software glitches or programming issues
  • Low battery voltage or power supply issues
  • Intermittent electrical connections

Common misdiagnoses

  • Faulty Body Control Module (BCM)
  • Wiring issues or shorts
  • Faulty connectors or terminals
  • Malfunctioning ignition switch
  • Battery or charging system problems
  • Faulty fuses
  • Other communication network issues (e.g., CAN bus problems)
  • Faulty or corroded ground connections
  • Issues with other control modules (e.g., PCM, ABS module)

Troubleshooting steps

  1. 1. Check for Other Codes

    Use an OBD-II scanner to check for any additional trouble codes. Sometimes, other codes can provide context or indicate related issues

  2. 2. Inspect the 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 damaged

  4. 4. Check Power and Ground

    Power Supply: Verify that the BCM is receiving the correct voltage. Use a multimeter to check the power supply to the module

  5. 5. Ground Connections

    Ensure that the ground connections for the BCM are secure and free of corrosion

  6. 6. Inspect the Body Control Module

    Module Condition: Check the BCM for any physical damage or signs of water intrusion

  7. 7. Reprogramming

    If the BCM has been replaced, it may need to be reprogrammed to the vehicle

  8. 8. Test Communication Lines

    CAN Bus Communication: Use a scan tool to check if the BCM is communicating with other modules on the CAN bus. If other modules are also not communicating, the issue may be with the bus itself

  9. 9. Wiring Issues

    If communication is lost, inspect the CAN bus wiring for shorts, opens, or other issues

  10. 10. Check for Software Updates

    Manufacturer Updates: Check if there are any software updates available for the BCM or other related modules from the vehicle manufacturer

  11. 11. Perform a Hard Reset

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

  12. 12. Scan Tool Functionality

    Ensure that the scan tool you are using is functioning properly and is compatible with your vehicle. Sometimes, communication issues can stem from the diagnostic tool itself

  13. 13. Consult Technical Service Bulletins (TSBs)

    Look for any TSBs related to the U0140 code for your specific vehicle make and model. Manufacturers may have specific fixes or recommendations

  14. 14. Seek Professional Help

    If the issue persists after performing the above steps, it may be necessary to consult a professional mechanic or dealership for further diagnosis. They may have specialized tools and knowledge to address complex issues.Conclusion Troubleshooting the U0140 code involves a systematic approach to check for wiring issues, module functionality, and communication integrity. Always ensure safety precautions are taken when working with vehicle electronics