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U code network High severity

U006C Control Module Communication Bus 'A' Off

The OBD2 code U006C indicates a communication issue where the control module is unable to communicate over the 'A' bus, typically due to a fault in the wiring, connectors, or the control module itself

Definition

The OBD2 code U006C indicates a communication issue where the control module is unable to communicate over the 'A' bus, typically due to a fault in the wiring, connectors, or the control module itself

Common causes

  • Faulty control module
  • Damaged wiring or connectors
  • Poor ground connections
  • Short circuit in the communication bus
  • Open circuit in the communication bus
  • Corroded connectors
  • Faulty or malfunctioning sensors
  • Software issues or programming errors
  • Battery or power supply issues
  • Interference from aftermarket devices

Common misdiagnoses

  • Faulty control module
  • Wiring issues
  • Poor ground connections
  • Corrupted software/firmware
  • Faulty sensors
  • Battery or charging system problems
  • Communication network issues
  • Faulty connectors or terminals
  • Intermittent electrical faults
  • Other communication bus errors

Troubleshooting steps

  1. 1. Check for Other Codes

    Start by scanning the vehicle for any other diagnostic trouble codes (DTCs). Other codes may provide additional context or indicate which module is having communication issues

  2. 2. Inspect Wiring and Connectors

  3. 3. Visually inspect the wiring and connectors associated with the control modules on Bus 'A'. 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 for Short Circuits

    Use a multimeter to check for short circuits in the wiring harness. Ensure that there are no shorts to ground or between wires

  6. 6. Test Control Modules

  7. 7. If you suspect a specific control module is causing the issue, you can test it by disconnecting it and checking if the communication bus returns to normal

  8. 8. If possible, swap the suspected module with a known good one to see if the problem persists

  9. 9. Inspect the CAN Bus

  10. 10. If your vehicle uses a Controller Area Network (CAN) bus, check the CAN bus wiring for continuity and resistance. The typical resistance should be around 60 ohms

  11. 11. Look for any damaged or pinched wires in the CAN bus circuit

  12. 12. Check for Software Updates

    Sometimes, communication issues can be resolved with a software update. Check with the manufacturer or a dealership to see if there are any updates available for the control modules

  13. 13. Battery and Power Supply

    Ensure that the vehicle's battery is in good condition and fully charged. Low voltage can cause communication issues between modules

  14. 14. Clear Codes and Test Drive

    After performing any repairs or inspections, clear the codes and take the vehicle for a test drive to see if the code returns

  15. 15. Professional Diagnosis

    If the issue persists after performing the above steps, it may be necessary to seek professional help. A qualified technician can use advanced diagnostic tools to further investigate the communication issue. By following these steps, you should be able to identify and resolve the underlying cause of the U006C code