WOMS
U code network Medium severity

U1987 U1987: "Module Communication Failure

The OBD2 code U1987 indicates a "Module Communication Failure," meaning there is a problem with communication between the vehicle's control modules, often due to a wiring issue, a faulty module, or a network problem

Definition

The OBD2 code U1987 indicates a "Module Communication Failure," meaning there is a problem with communication between the vehicle's control modules, often due to a wiring issue, a faulty module, or a network problem

Common causes

  • Faulty wiring or connectors
  • Failed or malfunctioning control module
  • Poor ground connections
  • Intermittent electrical issues
  • Software or firmware issues
  • Corroded terminals
  • Low battery voltage
  • Communication network issues (e.g., CAN bus problems)

Common misdiagnoses

  • Faulty wiring or connectors
  • Defective control module
  • Software issues or updates needed
  • Battery or power supply problems
  • Grounding issues
  • Intermittent communication issues
  • Other unrelated module failures

Troubleshooting steps

  1. 1. Check for Other 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

  3. 3. Visually inspect the wiring and connectors associated with the affected module. 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 Power Supply

    Ensure that the module in question is receiving the proper voltage and ground. Use a multimeter to check the power supply to the module

  6. 6. Test the Module

    If possible, test the affected module to ensure it is functioning correctly. This may involve using specialized diagnostic tools or swapping the module with a known good one

  7. 7. Check for Interference

    Look for any aftermarket devices or modifications that may interfere with the communication between modules. This includes things like alarm systems, stereo systems, or other electronic accessories

  8. 8. Inspect the CAN Bus

    If the vehicle uses a Controller Area Network (CAN) bus for communication, check the integrity of the CAN bus wiring. Look for shorts, opens, or other issues that could disrupt communication

  9. 9. Clear Codes and Test Drive

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

  10. 10. Update Software/Firmware

    In some cases, updating the software or firmware of the affected module may resolve communication issues. Check with the manufacturer for any available updates

  11. 11. Consult Technical Service Bulletins (TSBs)

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

  12. 12. Professional Diagnosis

    If the issue persists after performing the above steps, it may be necessary to seek the assistance of a professional mechanic or dealership with advanced diagnostic equipment. By following these steps, you can systematically identify and address the underlying cause of the U1987 code