WOMS
U code network High severity

U1835 U1835: "Control Module Communication Failure

The OBD2 code U1835 indicates a communication failure between control modules in a vehicle, suggesting that one or more modules are not able to communicate properly with each other

Definition

The OBD2 code U1835 indicates a communication failure between control modules in a vehicle, suggesting that one or more modules are not able to communicate properly with each other

Common causes

  • Faulty control module
  • Damaged wiring or connectors
  • Poor ground connections
  • Corroded terminals
  • Communication network issues (CAN bus problems)
  • Software glitches or outdated firmware
  • Interference from aftermarket devices
  • Low battery voltage or power supply issues

Common misdiagnoses

  • Faulty control module
  • Wiring issues
  • Poor ground connections
  • Corrupted software/firmware
  • Faulty sensors
  • Battery or power supply problems
  • Intermittent connection issues
  • Communication network faults (e.g., CAN bus 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 wiring harnesses that connect the affected modules

  4. 4. Check Power and Ground

    Ensure that the control modules have proper power and ground connections. Use a multimeter to check voltage and ground continuity

  5. 5. Verify that the fuses related to the control modules are intact

  6. 6. Test Control Modules

    If possible, test the affected control modules individually. This may involve using specialized diagnostic tools or software to communicate with the modules

  7. 7. If a specific module is unresponsive, it may need to be replaced

  8. 8. Inspect the CAN Bus

    The Controller Area Network (CAN) bus is responsible for communication between modules. Check for any issues with the CAN bus wiring, such as shorts or opens

  9. 9. Use an oscilloscope to monitor the CAN bus signals if you have access to one

  10. 10. Check for Software Updates

    Sometimes, communication issues can be resolved with a software update. Check with the vehicle manufacturer for any available updates for the control modules

  11. 11. Clear Codes and Test Drive

    After performing any repairs or inspections, clear the trouble codes using the OBD-II scanner and take the vehicle for a test drive to see if the code reappears

  12. 12. Consult Technical Service Bulletins (TSBs)

    Look for any TSBs related to the specific make and model of the vehicle. Manufacturers may have issued guidance on common issues related to U1835

  13. 13. Seek Professional Help

    If the issue persists after performing the above steps, it may be necessary to consult a professional mechanic or technician who has experience with the specific vehicle and its control systems.Conclusion Troubleshooting a U1835 code can be complex due to the nature of control module communication. Following these steps systematically can help identify and resolve the underlying issue. Always refer to the vehicle's service manual for specific procedures and specifications