WOMS
U code network Medium severity

U1504 Module Not Responding

The OBD2 code U1504 indicates that a communication issue has occurred, where a specific module in the vehicle's network is not responding to requests from the diagnostic tool or other modules

Definition

The OBD2 code U1504 indicates that a communication issue has occurred, where a specific module in the vehicle's network is not responding to requests from the diagnostic tool or other modules

Common causes

  • Faulty or disconnected wiring harness
  • Malfunctioning control module
  • Poor ground connection
  • Corroded connectors
  • Communication issues between modules
  • Software or firmware issues
  • Low battery voltage or power supply problems
  • Interference from aftermarket devices or modifications

Common misdiagnoses

  • Faulty wiring or connectors
  • Defective control module
  • Software issues or updates needed
  • Battery or power supply problems
  • Grounding issues
  • Communication network faults
  • Sensor malfunctions
  • Intermittent electrical 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 the Wiring and Connectors

    Visual Inspection: Check the wiring harness and connectors associated with the module that is not responding. Look for signs of damage, corrosion, or loose connections

  3. 3. Connector Pins

    Ensure that the pins in the connectors are not bent, corroded, or damaged

  4. 4. Check Power and Ground

    Power Supply: Verify that the module is receiving the correct voltage. Use a multimeter to check the power supply to the module

  5. 5. Ground Connection

    Ensure that the ground connection for the module is secure and functioning properly

  6. 6. Test the Module

    If possible, test the module itself. This may involve using a scan tool to communicate with the module or swapping it with a known good module if available

  7. 7. Inspect the CAN Bus

    CAN Bus Communication: U1504 often relates to communication issues on the Controller Area Network (CAN) bus. Check for any faults in the CAN bus wiring and ensure that all modules on the bus are functioning correctly

  8. 8. Termination Resistors

    Ensure that the CAN bus has the proper termination resistors in place

  9. 9. Check for Software Updates

    Sometimes, a software update for the vehicle’s modules can resolve communication issues. Check with the manufacturer for any available updates

  10. 10. Clear Codes and Test Drive

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

  11. 11. 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 U1504

  12. 12. Professional Diagnosis

    If the issue persists after performing the above steps, consider seeking help from a professional mechanic or dealership. They may have specialized tools and knowledge to diagnose complex communication issues.Conclusion Troubleshooting OBD-II code U1504 requires a systematic approach to identify the root cause of the communication failure. By following these steps, you can narrow down the potential issues and work towards a resolution