WOMS
U code network Medium severity

U1277 U1277: "Module Communication Failure

The OBD2 code U1277 indicates a "Module Communication Failure," meaning that there is a problem with communication between the vehicle's control modules, often due to a fault in the wiring, connectors, or the modules...

Definition

The OBD2 code U1277 indicates a "Module Communication Failure," meaning that there is a problem with communication between the vehicle's control modules, often due to a fault in the wiring, connectors, or the modules themselves

Common causes

  • Faulty wiring or connectors
  • Failed or malfunctioning control module
  • Corrupted software or firmware in the module
  • Poor ground connections
  • Intermittent electrical issues
  • Low battery voltage or weak battery
  • Communication network issues (e.g., CAN bus problems)
  • Damaged or corroded pins in connectors
  • Incompatible or improperly installed aftermarket components

Common misdiagnoses

  • Faulty wiring or connectors
  • Defective control module
  • Low battery voltage
  • Corroded terminals
  • Intermittent communication issues
  • Software glitches or updates needed
  • Grounding issues
  • Faulty sensors or actuators
  • Other communication codes misinterpreted
  • Environmental interference (e.g., moisture or temperature)

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, other codes can provide additional context for the U1277 code

  2. 2. Inspect Wiring and Connectors

  3. 3. Visually inspect the wiring and connectors associated with the affected module(s). 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 affected module is receiving the proper voltage. 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. Inspect the CAN Bus

  8. 8. If the vehicle uses a Controller Area Network (CAN) bus for communication, check the integrity of the CAN bus wiring

  9. 9. Look for shorts, opens, or high resistance in the CAN bus lines (usually CAN High and CAN Low)

  10. 10. Check for Interference

    Ensure that there are no aftermarket devices or modifications that could be interfering with the communication between modules

  11. 11. Reset the Codes

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

  12. 12. Update Software/Firmware

    In some cases, a software update for the vehicle's control modules may be necessary. Check with the manufacturer for any available updates

  13. 13. Consult Technical Service Bulletins (TSBs)

    Look for any TSBs related to the U1277 code for your specific vehicle make and model. Manufacturers may have specific recommendations or known issues

  14. 14. Professional Diagnosis

    If the issue persists after performing the above steps, consider seeking help from a professional mechanic or dealership with experience in diagnosing module communication issues. By following these steps, you can systematically identify and resolve the underlying cause of the U1277 code