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U1599Lost Communication with Vehicle Control Module

The OBD2 code U1599 indicates a loss of communication with a vehicle control module, suggesting that the module is not responding or is unable to communicate with other systems in the vehicle

Definition

The OBD2 code U1599 indicates a loss of communication with a vehicle control module, suggesting that the module is not responding or is unable to communicate with other systems in the vehicle

Common causes

  • Faulty Vehicle Control Module (VCM)
  • Damaged wiring or connectors
  • Poor ground connections
  • Corroded terminals
  • Faulty communication network (CAN bus issues)
  • Software or firmware issues
  • Battery or power supply problems
  • Intermittent electrical connections

Common misdiagnoses

  • Faulty Vehicle Control Module (VCM)
  • Wiring issues or shorts in the communication lines
  • Faulty connectors or terminals
  • Issues with other control modules (e.g., ECM, BCM)
  • Power supply problems to the control module
  • Software or firmware issues in the control module
  • Corrupted data or communication protocols
  • Grounding issues in the electrical system

Troubleshooting steps

  1. 1.Check for Additional Codes

    Use an OBD-II scanner to check for any other trouble codes that may be present. Other codes can provide additional context for the communication issue

  2. 2.Inspect Wiring and Connectors

  3. 3.Visually inspect the wiring and connectors associated with the affected control module. Look for signs of damage, corrosion, or loose connections

  4. 4.Pay special attention to the wiring harnesses that connect to the control modules

  5. 5.Check Power and Ground

  6. 6.Verify that the control module is receiving the proper power supply. Use a multimeter to check voltage at the module's power and ground pins

  7. 7.Ensure that the ground connections are secure and free of corrosion

  8. 8.Test the Control Module

  9. 9.If possible, test the control module itself to ensure it is functioning correctly. This may involve using specialized diagnostic equipment or swapping the module with a known good one

  10. 10.Inspect the CAN Bus

  11. 11.The communication between control modules often occurs over a Controller Area Network (CAN) bus. Check for any issues with the CAN bus wiring, such as shorts, opens, or interference

  12. 12.Use an oscilloscope to monitor the CAN bus signals if you have access to one

  13. 13.Check for Software Updates

  14. 14.Sometimes, communication issues can be resolved with a software update. Check with the vehicle manufacturer for any available updates for the control modules

  15. 15.Clear Codes and Test Drive

  16. 16.After performing any repairs or inspections, clear the trouble codes using the OBD-II scanner and take the vehicle for a test drive to see if the code reappears

  17. 17.Consult Technical Service Bulletins (TSBs)

  18. 18.Look for any TSBs related to the specific make and model of the vehicle. Manufacturers may have issued guidance on known issues that could be relevant

  19. 19.Seek Professional Help

  20. 20.If the issue persists after performing the above steps, it may be necessary to consult a professional mechanic or dealership with experience in diagnosing complex communication issues. By following these troubleshooting steps, you can systematically identify and resolve the underlying cause of the U1599 code