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U0108Lost Communication With Alternative Fuel Control Module

The OBD2 code U0108 indicates that there is a lost communication issue between the vehicle's main control module and the alternative fuel control module, which may affect the operation of alternative fuel systems

Definition

The OBD2 code U0108 indicates that there is a lost communication issue between the vehicle's main control module and the alternative fuel control module, which may affect the operation of alternative fuel systems

Common causes

  • Faulty Alternative Fuel Control Module
  • Damaged wiring or connectors
  • Poor electrical connections
  • Failed communication network (CAN bus issues)
  • Corroded terminals
  • Software or firmware issues
  • Blown fuses
  • Battery or power supply issues

Common misdiagnoses

  • Faulty Engine Control Module (ECM)
  • Wiring issues or damaged connectors
  • Faulty Alternative Fuel Control Module
  • Issues with the fuel system
  • Faulty sensors (e.g., fuel pressure sensor)
  • Battery or charging system problems
  • Corrupted software or firmware in the ECM
  • Grounding issues
  • Faulty communication lines or CAN bus issues
  • Other communication-related codes or issues

Troubleshooting steps

  1. 1.Check for Other Codes

    Use an OBD-II scanner to check for any additional trouble codes. Other codes may provide more context or indicate related issues

  2. 2.Inspect Wiring and Connectors

    Visual Inspection: Check the wiring harness and connectors associated with the alternative fuel control module for any signs of damage, corrosion, or loose connections

  3. 3.Repair or Replace

    Repair any damaged wires or connectors and ensure all connections are secure

  4. 4.Test the Alternative Fuel Control Module

    Power and Ground: Verify that the alternative fuel control module is receiving the correct power and ground signals. Use a multimeter to check voltage and continuity

  5. 5.Module Functionality

    If possible, test the module in another vehicle or replace it with a known good unit to see if the issue persists

  6. 6.Check Communication Lines

    CAN Bus Communication: Inspect the CAN bus lines for continuity and proper resistance. Ensure that there are no shorts or open circuits

  7. 7.Scan Tool Communication

    Use a scan tool to check if you can communicate with the alternative fuel control module. If not, it may indicate a problem with the module or the communication lines

  8. 8.Inspect Fuses

    Check the fuses related to the alternative fuel control module and the ECM. Replace any blown fuses

  9. 9.Look for Software Updates

    Check if there are any software updates available for the ECM or the alternative fuel control module. Sometimes, manufacturers release updates to fix communication issues

  10. 10.Reset the Codes

    After performing repairs, clear the 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 documented solutions for known issues

  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 a U0108 code involves a systematic approach to check for wiring issues, module functionality, and communication integrity. Always ensure safety precautions are taken when working on vehicle electrical systems