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U code network High severity

U1937 U1937: "Module Communication Failure

The OBD2 code U1937 indicates a "Module Communication Failure," meaning there is a problem with communication between vehicle modules, often due to a fault in the wiring, connectors, or the modules themselves

Definition

The OBD2 code U1937 indicates a "Module Communication Failure," meaning there is a problem with communication between vehicle modules, often due to a fault in the wiring, connectors, or the modules themselves

Common causes

  • Faulty wiring or connectors
  • Failed or malfunctioning control module
  • Corrupted software or firmware in the module
  • Poor ground connections
  • Interference from aftermarket devices
  • Low battery voltage or power supply issues
  • Communication network issues (e.g., CAN bus problems)

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 module failures in the network

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 the Affected Module

  6. 6. Identify which module is reporting the U1937 code. This could be a specific control module (e.g., ABS, BCM, etc.)

  7. 7. If possible, test the module by checking its power and ground supply. Ensure that it is receiving the correct voltage

  8. 8. Perform a Network Test

  9. 9. Use a scan tool capable of performing a network test to check the communication between modules. This can help identify if the issue is isolated to one module or if it affects multiple modules

  10. 10. Inspect the CAN Bus

  11. 11. If your vehicle uses a Controller Area Network (CAN) bus, check for issues with the bus itself. Look for short circuits, open circuits, or any other faults in the wiring

  12. 12. You can use an oscilloscope to check the signal integrity on the CAN bus lines

  13. 13. Check for Software Updates

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

  15. 15. Reset the Modules

  16. 16. Clear the trouble codes using a scan tool and see if the code returns. Sometimes, a temporary glitch can cause communication failures

  17. 17. Replace the Module

  18. 18. If all other troubleshooting steps fail and the module is determined to be faulty, consider replacing the affected control module

  19. 19. Consult Technical Service Bulletins (TSBs)

  20. 20. Check for any TSBs related to the U1937 code for your specific vehicle make and model. Manufacturers may have specific recommendations or known issues

  21. 21. Seek Professional Help

  22. 22. If you are unable to resolve the issue, consider seeking help from a qualified technician or automotive professional who has experience with your vehicle's make and model. By following these steps, you should be able to diagnose and potentially resolve the U1937 code. Always refer to the vehicle's service manual for specific procedures and specifications