WOMS
U code network Medium severity

U1720 U1720: "Module Communication Failure

The OBD2 code U1720 indicates a "Module Communication Failure," meaning there is a problem with communication between the vehicle's control modules

Definition

The OBD2 code U1720 indicates a "Module Communication Failure," meaning there is a problem with communication between the vehicle's control modules

Common causes

  • Faulty wiring or connectors
  • Failed or malfunctioning control module
  • Poor ground connections
  • Corrupted software or firmware in the module
  • Intermittent communication issues
  • Electrical interference
  • Low battery voltage or power supply issues
  • Damaged or corroded pins in connectors

Common misdiagnoses

  • Faulty wiring or connectors
  • Defective control module
  • Software issues or updates needed
  • Power supply problems
  • Grounding issues
  • Intermittent communication issues
  • Other communication protocol failures

Troubleshooting steps

  1. 1. Check for Other Codes

    Use an OBD-II scanner to check for any other trouble codes that may be present. Sometimes, multiple codes can provide more context for the issue

  2. 2. Inspect Wiring and Connectors

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

  4. 4. Pay special attention to the wiring harnesses that connect the modules, as these can be prone to wear and tear

  5. 5. Check Power and Ground

  6. 6. Ensure that the affected module has a proper power supply and ground connection. Use a multimeter to check voltage and ground continuity

  7. 7. If the module is not receiving power, trace the wiring back to the fuse box and check for blown fuses or damaged wires

  8. 8. Test the Module

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

  10. 10. Some modules may have self-diagnostic capabilities that can provide additional information

  11. 11. Check for Communication

  12. 12. Use a scan tool to check if the affected module is communicating with other modules. If it is not, there may be a fault in the module itself or in the communication network

  13. 13. Verify that the communication protocols (e.g., CAN, LIN) are functioning correctly

  14. 14. Inspect the CAN Bus

  15. 15. If the vehicle uses a Controller Area Network (CAN) bus, check for issues with the bus itself. Look for short circuits, open circuits, or interference that could disrupt communication

  16. 16. Use an oscilloscope to monitor the CAN signals if necessary

  17. 17. Update Software/Firmware

  18. 18. Check if there are any software or firmware updates available for the affected module. Sometimes, communication issues can be resolved with an update

  19. 19. Clear Codes and Test Drive

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

  21. 21. Consult Technical Service Bulletins (TSBs)

  22. 22. Look for any TSBs related to the specific make and model of the vehicle. Manufacturers may have issued guidance on common communication issues

  23. 23. Seek Professional Help

  24. 24. If the issue persists after following these steps, it may be necessary to consult a professional mechanic or technician who has experience with the specific vehicle and its systems. By following these troubleshooting steps, you can systematically identify and resolve the underlying cause of the U1720 code