WOMS
U code network Medium severity

U2773 U2773: Vehicle Communication Bus Malfunction

The OBD2 code U2773 indicates a malfunction in the vehicle communication bus, which affects the communication between various control modules in the vehicle

Definition

The OBD2 code U2773 indicates a malfunction in the vehicle communication bus, which affects the communication between various control modules in the vehicle

Common causes

  • Faulty wiring or connectors in the communication bus
  • Malfunctioning control modules
  • Corrupted software or firmware in control modules
  • Poor ground connections
  • Short circuits or open circuits in the communication lines
  • Interference from aftermarket devices
  • Damaged or defective OBD-II port
  • Low battery voltage or power supply issues

Common misdiagnoses

  • Faulty OBDII connector
  • Defective ECM (Engine Control Module)
  • Malfunctioning BCM (Body Control Module)
  • Wiring issues or shorts in the communication lines
  • Faulty sensors or actuators
  • Software glitches or outdated firmware
  • Battery or power supply issues
  • Corroded or loose connectors
  • Interference from aftermarket devices or modifications
  • Issues with the CAN bus system

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 Wiring and Connectors

    Visual Inspection: Check the wiring and connectors related to the communication bus (CAN bus) for any signs of damage, corrosion, or loose connections

  3. 3. Repair or Replace

    If any damaged wires or connectors are found, repair or replace them as necessary

  4. 4. Check for Short Circuits

    Use a multimeter to check for short circuits in the communication lines. Ensure that there are no unintended connections between the communication wires and ground or power

  5. 5. Test the Modules

    Module Functionality: Verify that all modules on the communication bus are functioning correctly. This may involve checking each module for fault codes and ensuring they are communicating properly

  6. 6. Reprogram or Reset

    If a specific module is found to be malfunctioning, it may need to be reprogrammed or reset

  7. 7. Inspect the CAN Bus

    Termination Resistors: Check the termination resistors at both ends of the CAN bus. Ensure they are present and functioning correctly

  8. 8. Bus Voltage

    Measure the voltage on the CAN bus to ensure it is within the expected range (typically around 2.5V when idle)

  9. 9. Check for Interference

    Look for any aftermarket devices or modifications that may be interfering with the communication bus. This includes alarms, stereo systems, or other electronic devices

  10. 10. Battery and Ground Connections

    Ensure that the vehicle's battery is in good condition and that all ground connections are secure. Poor battery voltage or ground issues can lead to communication problems

  11. 11. Perform a System Reset

    Disconnect the battery for a few minutes to reset the vehicle's computer systems. Reconnect and see if the code reappears

  12. 12. Consult Technical Service Bulletins (TSBs)

    Check for any manufacturer-specific TSBs related to the U2773 code. There may be known issues or recalls that could provide guidance

  13. 13. Professional Diagnosis

    If the issue persists after performing the above steps, consider seeking help from a professional mechanic or dealership. They may have specialized diagnostic tools and experience with your specific vehicle make and model.Conclusion Troubleshooting a U2773 code can be complex due to the nature of vehicle communication systems. Following these steps systematically can help identify and resolve the underlying issue. Always refer to the vehicle's service manual for specific procedures and specifications related to your vehicle