WOMS
U code network Medium severity

U1738 U1738: Control Module Communication Failure

The OBD2 code U1738 indicates a communication failure between control modules in a vehicle, suggesting that one or more modules are not properly communicating with each other

Definition

The OBD2 code U1738 indicates a communication failure between control modules in a vehicle, suggesting that one or more modules are not properly communicating with each other

Common causes

  • Faulty control module
  • Damaged wiring or connectors
  • Poor ground connections
  • Corroded terminals
  • Communication network issues (e.g., CAN bus problems)
  • Software glitches or outdated firmware
  • Intermittent electrical issues
  • Battery or power supply problems

Common misdiagnoses

  • Faulty control module
  • Wiring issues
  • Poor ground connections
  • Corrupted software or firmware
  • Faulty sensors
  • Communication network issues
  • Battery or power supply problems
  • Intermittent connection 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. This can provide more context about the issue

  2. 2. Inspect Wiring and Connectors

    Visual Inspection: Look for damaged, frayed, or corroded wiring and connectors related to the control modules

  3. 3. Connector Integrity

    Ensure that all connectors are securely attached and free of corrosion or dirt

  4. 4. Check Power and Ground

    Verify that the affected control module has the proper power supply and ground. Use a multimeter to check voltage and ground continuity

  5. 5. Test Control Modules

    If possible, test the affected control module for proper operation. This may involve using specialized diagnostic tools or swapping with a known good module

  6. 6. Inspect the CAN Bus

    The Controller Area Network (CAN) bus is responsible for communication between modules. Check for

  7. 7. Short circuits or open circuits in the CAN bus wiring

  8. 8. Termination resistors at the ends of the CAN bus; ensure they are present and functioning

  9. 9. Check for Interference

    Look for any aftermarket devices or modifications that may interfere with the vehicle's communication network

  10. 10. Perform a Network Test

    Use a scan tool capable of performing a network test to check for communication between modules. This can help identify which module is not communicating

  11. 11. Clear Codes and Test Drive

    After performing checks and repairs, clear the trouble codes and take the vehicle for a test drive to see if the code returns

  12. 12. Seek Professional Help

    If the issue persists after performing the above steps, consider seeking assistance from a qualified technician or automotive specialist who has experience with your vehicle's make and model. By following these steps, you can systematically diagnose and address the underlying issues causing the U1738 code