WOMS
U code network High severity

U2179 Lost Communication with the Body Control Module (BCM) - Bus Off

The OBD2 code U2179 indicates a loss of communication with the Body Control Module (BCM) due to a "Bus Off" condition, meaning the BCM is not responding on the communication network, often due to a fault in the wiring,...

Definition

The OBD2 code U2179 indicates a loss of communication with the Body Control Module (BCM) due to a "Bus Off" condition, meaning the BCM is not responding on the communication network, often due to a fault in the wiring, connectors, or the module itself

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
  • Intermittent electrical issues
  • Malfunctioning other modules on the CAN bus
  • Software issues or programming errors in the BCM
  • Battery or power supply issues affecting the BCM

Common misdiagnoses

  • Faulty Body Control Module (BCM)
  • Wiring issues or damaged connectors
  • Faulty Instrument Cluster
  • Power supply issues
  • Faulty CAN bus communication lines
  • Faulty or corroded ground connections
  • Issues with other control modules
  • Software or firmware issues in the BCM or other modules

Troubleshooting steps

  1. 1. Check for Additional Codes

    Use an OBD-II scanner to check for any other trouble codes that may be present. This can provide more context and help identify related issues

  2. 2. Inspect the Wiring and Connectors

    Visual Inspection: Check the wiring harness and connectors related to the BCM for any signs of damage, corrosion, or loose connections

  3. 3. Connector Pins

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

  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 CAN Bus

    Bus Communication: The U2179 code often relates to issues with the Controller Area Network (CAN) bus. Check for proper communication between the BCM and other modules

  7. 7. Termination Resistors

    Ensure that the CAN bus has the correct termination resistors in place and that they are functioning properly

  8. 8. Check for Short Circuits or Open Circuits

    Use a multimeter to check for shorts or opens in the wiring that connects the BCM to other modules and the CAN bus

  9. 9. Scan for Communication Issues

    Use a professional scan tool to monitor live data and check for communication between the BCM and other modules. Look for any modules that are not responding

  10. 10. Inspect for Environmental Factors

    Check for moisture or water intrusion in the BCM area, as this can cause communication issues. Look for signs of rust or corrosion

  11. 11. Reset the System

    After performing checks and repairs, clear the codes using the OBD-II scanner and see if the code returns after a test drive

  12. 12. Consult Technical Service Bulletins (TSBs)

    Look for any TSBs related to the specific make and model of the vehicle, as manufacturers may have issued guidance on common issues related to the BCM

  13. 13. Seek Professional Help

    If the issue persists after performing these steps, it may be necessary to consult a professional mechanic or automotive technician who has experience with the specific vehicle and its systems. By following these steps, you should be able to identify the root cause of the U2179 code and take appropriate action to resolve the communication issue with the Body Control Module