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U2735 U2735: Control Module Communication Bus Fault

The OBD2 code U2735: Control Module Communication Bus Fault indicates a problem with the communication between control modules in a vehicle, suggesting that one or more modules are not properly transmitting or receiving...

Definition

The OBD2 code U2735: Control Module Communication Bus Fault indicates a problem with the communication between control modules in a vehicle, suggesting that one or more modules are not properly transmitting or receiving data on the communication bus

Common causes

  • Faulty control module
  • Damaged wiring or connectors
  • Poor ground connections
  • Corroded terminals
  • Intermittent electrical connections
  • Software issues or bugs
  • Faulty communication bus (CAN bus) components
  • Low battery voltage or power supply issues

Common misdiagnoses

  • Faulty control module
  • Wiring issues or shorts
  • Corroded connectors
  • Power supply problems
  • Software glitches or updates needed
  • Faulty sensors
  • Incorrectly installed aftermarket components
  • Grounding issues

Troubleshooting steps

  1. 1. Check for Additional 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

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

  3. 3. Pay special attention to the communication bus wires (CAN bus) for any signs of wear or damage

  4. 4. Check for Short Circuits or Open Circuits

    Use a multimeter to check for continuity in the communication lines. Look for any short circuits or open circuits that could disrupt communication

  5. 5. Test Control Modules

    If possible, test the individual control modules for proper operation. This may involve using specialized diagnostic tools or software

  6. 6. If a specific module is suspected to be faulty, consider replacing it or reprogramming it if necessary

  7. 7. Inspect Ground Connections

    Ensure that all ground connections for the control modules are secure and free of corrosion. Poor grounding can lead to communication issues

  8. 8. Check for Interference

    Look for any aftermarket devices or modifications that may interfere with the communication bus. This includes alarms, stereo systems, or other electronic devices

  9. 9. Scan Tool Communication

    Use a scan tool to communicate with each control module individually. If some modules respond while others do not, it may indicate a problem with the non-responding modules

  10. 10. Battery and Power Supply Check

    Ensure that the vehicle's battery is in good condition and that the voltage is within the normal range. Low voltage can cause communication issues

  11. 11. Check the fuses related to the control modules and communication bus

  12. 12. Software Updates

    Check if there are any software updates available for the vehicle's control modules. Sometimes, manufacturers release updates to fix communication issues

  13. 13. 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.1

  14. 14. Consult Technical Service Bulletins (TSBs)

    Look for any TSBs related to the specific make and model of the vehicle. Manufacturers may have documented solutions for known issues.1

  15. 15. Professional Diagnosis

    If the issue persists after performing the above steps, consider seeking help from a professional mechanic or dealership with experience in diagnosing communication issues. By following these steps, you should be able to identify and resolve the underlying cause of the U2735 code