WOMS
U code network High severity

U1969 Lost Communication with the Body Control Module (BCM)"

The OBD2 code U1969 indicates that there is a communication failure between the vehicle's control module and the Body Control Module (BCM), which may affect various electrical functions and systems in the vehicle

Definition

The OBD2 code U1969 indicates that there is a communication failure between the vehicle's control module and the Body Control Module (BCM), which may affect various electrical functions and systems in the vehicle

Common causes

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

Common misdiagnoses

  • Faulty Body Control Module (BCM)
  • Wiring issues or shorts in the communication lines
  • Faulty or corroded connectors
  • Issues with the power supply to the BCM
  • Faulty Instrument Cluster
  • Malfunctioning Engine Control Module (ECM)
  • Problems with other control modules in the network
  • Software or firmware issues in the BCM
  • Battery or charging system problems
  • Grounding issues in the vehicle's electrical system

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 leading to the 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. Check Power and Ground

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

  5. 5. Ground Connections

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

  6. 6. Inspect the BCM

    Physical Condition: Check the BCM for any signs of physical damage, such as cracks or burn marks

  7. 7. Reprogramming

    If the BCM has been replaced, ensure that it has been properly programmed to the vehicle

  8. 8. Test Communication Lines

    CAN Bus: Use a scan tool to check the communication on the CAN bus. If other modules are not communicating, there may be a fault in the bus itself

  9. 9. Scope Testing

    If available, use an oscilloscope to check for proper signal patterns on the communication lines

  10. 10. Check for Intermittent Issues

    Temperature Sensitivity: Sometimes, issues can be temperature-related. Check if the problem occurs only under certain conditions (e.g., after the vehicle has been running for a while)

  11. 11. Vibration

    Check if the issue occurs when the vehicle is in motion or over bumps

  12. 12. Inspect Related Modules

    If the BCM is not communicating, check other modules that may be connected to the same communication network. A fault in one module can affect communication with others

  13. 13. Perform a Hard Reset

    Disconnect the battery for a few minutes to reset the vehicle’s electronic systems. Reconnect and see if the code reappears

  14. 14. Consult Technical Service Bulletins (TSBs)

    Check for any TSBs related to the BCM or communication issues for your specific vehicle make and model. Manufacturers may have known fixes for common problems

  15. 15. 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 a U1969 code can be complex, as it often involves multiple systems and components. Following these steps systematically can help identify the root cause of the communication loss with the BCM