WOMS
U code network High severity

U1702 refers to a communication issue between the transmission control module (TCM) and the engine control module (ECM)

The OBD2 code U1702 indicates a communication issue between the Transmission Control Module (TCM) and the Engine Control Module (ECM), suggesting a failure in data exchange or signal transmission between these two...

Definition

The OBD2 code U1702 indicates a communication issue between the Transmission Control Module (TCM) and the Engine Control Module (ECM), suggesting a failure in data exchange or signal transmission between these two components

Common causes

  • Faulty Transmission Control Module (TCM)
  • Faulty Engine Control Module (ECM)
  • Damaged or corroded wiring harness
  • Poor electrical connections
  • Faulty CAN bus communication
  • Blown fuses
  • Software issues or programming errors
  • Grounding issues
  • Faulty sensors related to transmission or engine
  • Intermittent electrical issues

Common misdiagnoses

  • Faulty Transmission Control Module (TCM)
  • Faulty Engine Control Module (ECM)
  • Wiring issues or damaged connectors
  • Faulty sensors (e.g., speed sensors)
  • Low transmission fluid levels
  • Transmission solenoid issues
  • Battery or charging system problems
  • Grounding issues
  • Software or firmware issues in the TCM or ECM
  • Incorrectly installed aftermarket components or modifications

Troubleshooting steps

  1. 1. Check for Additional Codes

    Start by scanning the vehicle for any other trouble codes. Sometimes, multiple codes can provide more context for the issue

  2. 2. Inspect Wiring and Connectors

  3. 3. Visually inspect the wiring harness and connectors between the TCM and ECM for any signs of damage, corrosion, or loose connections

  4. 4. Ensure that all connectors are securely plugged in and that there are no bent pins

  5. 5. Check for Short Circuits or Open Circuits

  6. 6. Use a multimeter to check for continuity in the wiring between the TCM and ECM. Look for any shorts to ground or open circuits that could be causing communication issues

  7. 7. Inspect Ground Connections

  8. 8. Ensure that the ground connections for both the TCM and ECM are clean, tight, and free of corrosion. Poor ground connections can lead to communication problems

  9. 9. Test the TCM and ECM

  10. 10. If the wiring and connections appear to be in good condition, you may need to test the TCM and ECM for proper operation. This may involve using a scan tool to check for communication with each module

  11. 11. Check for Software Updates

  12. 12. Sometimes, communication issues can be resolved with a software update. Check with the manufacturer or a dealership to see if there are any available updates for the TCM or ECM

  13. 13. Inspect the CAN Bus

  14. 14. If your vehicle uses a Controller Area Network (CAN) for communication, check the CAN bus for any issues. This may involve checking the resistance and voltage levels on the CAN lines

  15. 15. Clear Codes and Test Drive

  16. 16. After performing the above checks and repairs, clear the trouble codes and take the vehicle for a test drive to see if the code returns

  17. 17. Consult Technical Service Bulletins (TSBs)

  18. 18. Look for any TSBs related to the U1702 code for your specific vehicle make and model. Manufacturers may have specific recommendations or known issues that can help in troubleshooting

  19. 19. Professional Diagnosis

  20. 20. If you are unable to resolve the issue after these steps, it may be necessary to seek the help of a professional mechanic or technician who has experience with your vehicle's specific systems. By following these steps, you can systematically diagnose and potentially resolve the communication issue indicated by the U1702 code