WOMS
U code network Medium severity

U2847 U2847: Vehicle Communication Bus Malfunction

The OBD2 code U2847: Vehicle Communication Bus Malfunction indicates a problem with the communication between various control modules in the vehicle, which may affect their ability to exchange data properly

Definition

The OBD2 code U2847: Vehicle Communication Bus Malfunction indicates a problem with the communication between various control modules in the vehicle, which may affect their ability to exchange data properly

Common causes

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

Common misdiagnoses

  • Faulty ECM (Engine Control Module)
  • Defective BCM (Body Control Module)
  • Wiring issues or shorts in the communication lines
  • Bad ground connections
  • Faulty sensors or actuators
  • Issues with the CAN bus system
  • Corrupted software or firmware in control modules
  • Battery or power supply problems
  • Intermittent connection issues
  • Faulty diagnostic tools or connectors

Troubleshooting steps

  1. 1. Check for Additional Codes

    Use an OBD-II scanner to check for any other related trouble codes. Addressing other codes may help resolve the U2847 code

  2. 2. Inspect Wiring and Connectors

    Visual Inspection: Check the wiring and connectors associated with the communication bus (CAN bus) 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. Check for Short Circuits

    Use a multimeter to check for short circuits in the communication lines. Look for continuity between the CAN high and CAN low wires and ground

  5. 5. Test the Control Modules

    Module Functionality: Verify that all control modules are functioning properly. A malfunctioning module can disrupt communication

  6. 6. Reprogram or Replace

    If a specific module is identified as faulty, consider reprogramming or replacing it

  7. 7. Inspect the CAN Bus

    Termination Resistors: Ensure that the CAN bus has the correct termination resistors at both ends. A missing or faulty resistor can cause communication issues

  8. 8. Bus Voltage

    Check the voltage levels on the CAN bus. The typical voltage levels should be around 2.5V for idle and can vary when data is being transmitted

  9. 9. Check for Interference

    Look for any aftermarket devices or modifications that may interfere with the vehicle's communication systems. Remove or disconnect these devices to see if the issue resolves

  10. 10. Scan Tool Communication

    Ensure that your OBD-II scanner is functioning correctly and can communicate with the vehicle. Try using a different scanner if necessary

  11. 11. Battery and Ground Connections

    Check the vehicle's battery and ground connections. A weak battery or poor ground can lead to communication issues

  12. 12. Software Updates

    Check if there are any software updates available for the vehicle's control modules. Sometimes, manufacturers release updates to fix communication issues

  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 tools and knowledge to diagnose complex communication issues.Conclusion Troubleshooting a U2847 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 guidance related to your make and model