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U1707 CAN Communication Bus Fault

The OBD2 code U1707 indicates a fault in the CAN (Controller Area Network) communication bus, suggesting a communication issue between modules in the vehicle's network

Definition

The OBD2 code U1707 indicates a fault in the CAN (Controller Area Network) communication bus, suggesting a communication issue between modules in the vehicle's network

Common causes

  • Faulty CAN bus wiring or connectors
  • Defective CAN bus module
  • Short circuit in the CAN bus
  • Open circuit in the CAN bus
  • Interference from other electrical components
  • Poor ground connections
  • Faulty or incompatible aftermarket accessories
  • Software or firmware issues in the control modules

Common misdiagnoses

  • Faulty Engine Control Module (ECM)
  • Faulty Transmission Control Module (TCM)
  • Bad wiring or connectors
  • Faulty Body Control Module (BCM)
  • Defective sensors
  • Battery or charging system issues
  • Faulty CAN bus transceiver
  • Software issues or updates needed
  • Grounding issues
  • Intermittent electrical connections

Troubleshooting steps

  1. 1. Check for Additional Codes

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

  2. 2. Inspect the Wiring and Connectors

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

  3. 3. Pay special attention to the connectors at the ECM (Engine Control Module) and other modules on the CAN bus

  4. 4. Test the CAN Bus Voltage

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

  5. 5. If the voltage levels are outside the expected range, there may be a short or open circuit

  6. 6. Check for Short Circuits

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

  7. 7. Verify Module Functionality

    Check if all modules on the CAN bus are functioning properly. If one module is malfunctioning, it can disrupt communication

  8. 8. You may need to perform a module scan to identify any non-communicating modules

  9. 9. Inspect for Interference

    Look for any sources of electrical interference that could be affecting the CAN bus communication. This could include aftermarket accessories or modifications

  10. 10. Check for Software Updates

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

  11. 11. Perform a Network Test

    If you have access to a professional scan tool, perform a network test to check the integrity of the CAN bus. This can help identify any communication issues between modules

  12. 12. Clear Codes and Test Drive

    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

  13. 13. Consult a Professional

    If the issue persists after performing these steps, it may be necessary to consult a professional technician or a dealership for further diagnosis.Additional Tips: - Always refer to the vehicle’s service manual for specific wiring diagrams and troubleshooting procedures. - Ensure that you have the proper tools and equipment to perform the tests safely and accurately. By following these steps, you should be able to identify and resolve the underlying issue causing the U1707 code