WOMS
U code network Medium severity

U1927 U1927: "Module Communication Failure

The OBD2 code U1927 indicates a "Module Communication Failure," meaning there is a problem with communication between vehicle modules, often due to a fault in wiring, connectors, or the modules themselves

Definition

The OBD2 code U1927 indicates a "Module Communication Failure," meaning there is a problem with communication between vehicle modules, often due to a fault in wiring, connectors, or the modules themselves

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
  • Battery or power supply problems
  • Grounding issues
  • Intermittent communication issues
  • Other communication protocol failures
  • Sensor malfunctions

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 module. Look for signs of damage, corrosion, or loose connections

  4. 4. Pay special attention to the ground connections, as poor grounding can lead to communication issues

  5. 5. Check Power Supply

  6. 6. Ensure that the affected module is receiving the proper voltage and ground. Use a multimeter to check the power supply to the module

  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 by swapping it with a known good module (if applicable) to see if the problem persists

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

  11. 11. Inspect the CAN Bus

  12. 12. If the vehicle uses a Controller Area Network (CAN) bus for communication, check the integrity of the CAN bus wiring. Look for shorts, opens, or interference

  13. 13. Use an oscilloscope to check the CAN bus signals if you have access to one. The signals should have a specific voltage range and waveform

  14. 14. Check for Software Updates

  15. 15. Sometimes, communication issues can be resolved with a software update. Check with the vehicle manufacturer or a dealership to see if there are any available updates for the affected module

  16. 16. Clear Codes and Test Drive

  17. 17. 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 returns

  18. 18. Consult Technical Service Bulletins (TSBs)

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

  20. 20. Professional Diagnosis

  21. 21. If the issue persists after performing the above steps, it may be necessary to seek the help of a professional mechanic or automotive technician who has experience with the specific vehicle and its systems. By following these steps, you can systematically diagnose and potentially resolve the U1927 code