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U code network High severity

U1002 Control Module Communication Bus Off

The OBD2 code U1002 indicates a communication issue where a control module is not able to communicate over the vehicle's communication bus, often due to a fault in the module or wiring

Definition

The OBD2 code U1002 indicates a communication issue where a control module is not able to communicate over 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
  • Short circuits in the communication lines
  • Corroded connectors
  • Faulty or damaged communication bus (CAN bus)
  • Interference from aftermarket devices
  • Software issues or programming errors
  • Low battery voltage or power supply issues
  • Faulty sensors or actuators affecting communication

Common misdiagnoses

  • Faulty control module
  • Wiring issues
  • Poor ground connections
  • Corrupted software/firmware
  • Faulty sensors
  • Battery or power supply issues
  • Communication network problems
  • Intermittent connection issues
  • Other communication bus errors
  • 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. Codes related to other modules can provide clues about the source of the problem

  2. 2. Inspect Wiring and Connectors

    Visually inspect the wiring and connectors associated with the control modules. Look for signs of damage, corrosion, loose connections, or broken wires. Pay special attention to the connectors for the modules that are not communicating

  3. 3. Check Power and Ground

    Ensure that the affected control module(s) have proper power and ground connections. Use a multimeter to verify voltage and ground continuity

  4. 4. Test the Communication Bus

    Use a scan tool to monitor the communication bus (CAN bus, LIN bus, etc.). Check for proper voltage levels and signal integrity. You may need an oscilloscope for more detailed analysis

  5. 5. Disconnect Modules

    If multiple modules are connected to the same communication bus, try disconnecting them one at a time to isolate the faulty module. After disconnecting a module, check if the communication is restored

  6. 6. Check for Short Circuits

    Inspect the wiring for any short circuits that may be causing the bus to go offline. This can include shorts to ground or to other wires

  7. 7. Inspect for Interference

    Look for any aftermarket devices or modifications that may be interfering with the communication bus. This can include alarms, stereo systems, or other electronic devices

  8. 8. Update or Reprogram Modules

    In some cases, a software update or reprogramming of the affected control module may be necessary. Check with the manufacturer for any available updates

  9. 9. Replace Faulty Module

    If a specific module is identified as faulty and cannot be repaired, it may need to be replaced. Ensure that the replacement module is compatible with your vehicle

  10. 10. Clear Codes and Test Drive

    After performing repairs, clear the trouble codes and take the vehicle for a test drive to see if the code returns. Monitor the communication bus during the drive. 1