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U1864 CAN Bus Communication Failure

The OBD2 code U1864: CAN Bus Communication Failure indicates a problem with the communication between modules on the Controller Area Network (CAN) bus, suggesting that one or more modules are not able to send or receive...

Definition

The OBD2 code U1864: CAN Bus Communication Failure indicates a problem with the communication between modules on the Controller Area Network (CAN) bus, suggesting that one or more modules are not able to send or receive data properly

Common causes

  • Faulty CAN bus wiring or connectors
  • Short circuit in the CAN bus
  • Open circuit in the CAN bus
  • Malfunctioning control modules
  • Poor ground connections
  • Interference from other electrical components
  • Corroded or damaged connectors
  • Software issues or bugs in the control modules
  • Low battery voltage or power supply issues
  • Faulty termination resistors

Common misdiagnoses

  • Faulty CAN Bus wiring
  • Defective ECU (Electronic Control Unit)
  • Bad ground connections
  • Malfunctioning sensors
  • Corrupted software or firmware
  • Faulty connectors or terminals
  • Interference from aftermarket devices
  • Low battery voltage or power supply issues
  • Incorrectly configured or incompatible modules
  • Physical damage to the CAN Bus network

Troubleshooting steps

  1. 1. Check for Other Codes

    Use an OBD-II scanner to check for any additional trouble codes. Other codes may provide more context about the issue

  2. 2. Inspect Wiring and Connectors

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

  4. 4. Pay special attention to the connectors on the Engine Control Module (ECM), Transmission Control Module (TCM), and any other modules that communicate over the CAN bus

  5. 5. Test the CAN Bus Voltage

  6. 6. Use a multimeter to check the voltage levels on the CAN High (CAN H) and CAN Low (CAN L) wires. The typical voltage levels should be around 2.5V when the bus is idle

  7. 7. If the voltage levels are outside the normal range, there may be a short circuit or an open circuit in the wiring

  8. 8. Check for Short Circuits

  9. 9. Inspect the CAN bus wiring for any short circuits to ground or to each other. This can cause communication failures

  10. 10. Test Individual Modules

  11. 11. Disconnect each module on the CAN bus one at a time and check if the code clears. This can help identify if a specific module is causing the communication failure

  12. 12. Check for Interference

  13. 13. Ensure that there are no aftermarket devices or modifications that could be interfering with the CAN bus communication

  14. 14. Inspect the Ground Connections

  15. 15. Check the ground connections for the control modules. Poor grounding can lead to communication issues

  16. 16. Scan for Module Communication

  17. 17. Use a scan tool to check if you can communicate with all the modules on the CAN bus. If some modules are unresponsive, it may indicate a problem with those specific modules

  18. 18. Check for Software Updates

  19. 19. Sometimes, a software update for the vehicle's control modules can resolve communication issues. Check with the manufacturer for any available updates

  20. 20. Replace Faulty Components

  21. 21. If a specific module is identified as faulty, it may need to be replaced. Ensure that the replacement module is compatible with the vehicle. 1

  22. 22. Consult Technical Service Bulletins (TSBs)

  23. 23. Check for any TSBs related to the U1864 code for your specific vehicle make and model. Manufacturers may have specific recommendations for addressing this issue. 1

  24. 24. Professional Diagnosis

  25. 25. If the issue persists after performing these steps, consider seeking help from a professional mechanic or dealership with experience in diagnosing CAN bus communication issues. By following these troubleshooting steps, you can systematically identify and resolve the underlying cause of the U1864 code