WOMS
U code network High severity

U2147 Lost Communication with the Body Control Module (BCM) - Bus Off

The OBD2 code U2147 indicates that there is a communication failure between the vehicle's control modules, specifically indicating that the Body Control Module (BCM) is not responding or is offline, often due to a bus...

Definition

The OBD2 code U2147 indicates that there is a communication failure between the vehicle's control modules, specifically indicating that the Body Control Module (BCM) is not responding or is offline, often due to a bus communication issue

Common causes

  • Faulty Body Control Module (BCM)
  • Damaged wiring or connectors in the communication circuit
  • Faulty or damaged CAN bus
  • Poor ground connections
  • Short circuits in the wiring
  • Corroded connectors
  • Malfunctioning other modules on the CAN bus
  • Software issues or programming errors in the BCM
  • Battery or power supply issues affecting the BCM
  • Interference from aftermarket accessories or modifications

Common misdiagnoses

  • Faulty Body Control Module (BCM)
  • Wiring issues or damaged connectors
  • Faulty or corroded ground connections
  • Issues with the CAN bus system
  • Faulty power supply to the BCM
  • Other module failures (e.g., ECM, TCM)
  • Software or firmware issues in the BCM
  • Battery or charging system problems

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 the Wiring and Connectors

    Visual Inspection: Look for damaged, frayed, or corroded wiring and connectors related to the BCM and the communication bus

  3. 3. Connector Integrity

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

  4. 4. Check the BCM

    Power and Ground: Verify that the BCM is receiving proper power and ground. Use a multimeter to check voltage at the BCM connector

  5. 5. Functionality

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

  6. 6. Inspect the Communication Bus

    CAN Bus Integrity: Check the integrity of the CAN bus wiring. Look for shorts, opens, or high resistance in the bus lines

  7. 7. Termination Resistors

    Ensure that the CAN bus has the correct termination resistors in place (typically 120 ohms at each end of the bus)

  8. 8. Check for Interference

    Electrical Interference: Look for sources of electrical interference that could disrupt communication, such as aftermarket accessories or modifications

  9. 9. Grounding Issues

    Ensure that the vehicle's grounding points are clean and secure

  10. 10. Scan for Communication Issues

    Use a scan tool to monitor the communication between the BCM and other modules. Check if other modules are reporting communication issues as well

  11. 11. Perform a Hard Reset

    Disconnect the vehicle's battery for a few minutes to reset the BCM and other modules. Reconnect and see if the code reappears

  12. 12. Check for Software Updates

    Verify if there are any software updates available for the BCM or other related modules. Sometimes, manufacturers release updates to fix communication issues

  13. 13. Consult Technical Service Bulletins (TSBs)

    Look for any TSBs related to the U2147 code for your specific vehicle make and model. Manufacturers may have documented common fixes or known issues

  14. 14. 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 U2147 involves a systematic approach to check for wiring issues, BCM functionality, and communication integrity. By following these steps, you can often identify the root cause of the problem and take appropriate action to resolve it