WOMS
U code network High severity

U1959 Lost Communication with Body Control Module (BCM)"

The OBD2 code U1959 indicates that there is a communication failure between the vehicle's control modules and the Body Control Module (BCM), which may affect various electrical functions and systems in the vehicle

Definition

The OBD2 code U1959 indicates that there is a communication failure between the vehicle's control modules 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
  • Poor ground connections
  • Faulty communication network (CAN bus issues)
  • Blown fuses
  • Software or firmware issues in the BCM
  • 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 power supply to the BCM
  • Problems with other control modules
  • Software or firmware issues in the BCM
  • Faulty ignition switch
  • Battery or charging system problems
  • Grounding issues
  • Faulty sensors or actuators related to the BCM

Troubleshooting steps

  1. 1. Check for Other Codes

    Use an OBD-II scanner to check for any additional trouble codes. Other codes may provide more 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 or water intrusion

  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, the issue may be with 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

    Look for issues that may arise from vibration or movement, which could affect connections

  12. 12. Inspect Related Modules

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

  13. 13. 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

  14. 14. Consult Technical Service Bulletins (TSBs)

    Check for any manufacturer-specific TSBs related to the U1959 code or BCM issues. There may be known fixes or recalls

  15. 15. Replace the BCM (if necessary)

    If all other troubleshooting steps fail and the BCM is determined to be faulty, consider replacing it. Ensure proper programming and configuration after replacement.1

  16. 16. Seek Professional Help

    If you are unable to resolve the issue, it may be best to consult a professional mechanic or automotive technician who has experience with your specific vehicle make and model. By following these steps, you should be able to identify the root cause of the U1959 code and take appropriate action to resolve the communication issue with the Body Control Module