WOMS
U code network High severity

U2377 Control Module Communication Bus Off

The OBD2 code U2377 indicates a communication issue where a control module is unable to communicate on the vehicle's communication bus, often due to a fault in the module or wiring

Definition

The OBD2 code U2377 indicates a communication issue where a control module is unable to communicate on the vehicle's communication bus, often due to a fault in the module or wiring

Common causes

  • Faulty control module
  • Damaged wiring or connectors
  • Poor ground connections
  • Communication bus interference
  • Software issues or bugs
  • Low battery voltage
  • Faulty or disconnected sensors
  • Corroded terminals or connectors

Common misdiagnoses

  • Faulty control module
  • Wiring issues
  • Poor ground connections
  • Corrupted software/firmware
  • Faulty sensors
  • Battery or power supply issues
  • Communication network problems
  • Incorrectly installed aftermarket accessories

Troubleshooting steps

  1. 1. Check for Additional Codes

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

  2. 2. Inspect Wiring and Connectors

    Visually inspect the wiring and connectors related to the control modules on the communication bus. Look for signs of damage, corrosion, or loose connections

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

  4. 4. Check Power Supply

    Ensure that the control modules have the proper power supply. Use a multimeter to check voltage at the module connectors

  5. 5. Verify that fuses related to the control modules are intact

  6. 6. Test the Control Modules

    If possible, test the affected control module(s) for functionality. This may involve using specialized diagnostic tools or swapping with a known good module

  7. 7. Check for any software updates or reprogramming that may be required for the control module

  8. 8. Inspect the Communication Bus

    Check the integrity of the communication bus (CAN bus, LIN bus, etc.). Look for shorts, opens, or resistance issues in the bus wiring

  9. 9. Use an oscilloscope or a CAN bus analyzer to monitor the communication signals and ensure they are within specifications

  10. 10. Clear Codes and Test Drive

    After performing inspections and repairs, clear the trouble codes using the OBD-II scanner

  11. 11. Take the vehicle for a test drive to see if the code reappears. Monitor the performance of the control modules during the drive

  12. 12. Check for Environmental Factors

    Sometimes, environmental factors such as moisture or temperature can affect module performance. Ensure that the modules are not exposed to excessive moisture or heat

  13. 13. Consult Technical Service Bulletins (TSBs)

    Check for any TSBs related to the specific make and model of the vehicle. Manufacturers may have issued guidance on common issues related to the U2377 code

  14. 14. Seek Professional Help

    If the issue persists after performing the above steps, it may be necessary to consult a professional technician or a dealership for further diagnosis. By following these troubleshooting steps, you can systematically identify and resolve the underlying issue causing the U2377 code