WOMS
U code network High severity

U1852 Lost Communication with Body Control Module (BCM) - Bus Off

The OBD2 code U1852 indicates that there is 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, likely due to a fault...

Definition

The OBD2 code U1852 indicates that there is 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, likely due to a fault in the wiring, module, or network

Common causes

  • Faulty Body Control Module (BCM)
  • Damaged wiring or connectors in the communication circuit
  • Short circuit or open circuit in the CAN bus
  • Faulty or corroded ground connections
  • Malfunctioning or damaged CAN bus transceiver
  • Issues with other modules on the CAN bus
  • Software or firmware issues in the BCM
  • Low battery voltage or power supply issues

Common misdiagnoses

  • Faulty Body Control Module (BCM)
  • Wiring issues or shorts in the communication lines
  • Faulty or corroded connectors
  • Issues with the power supply to the BCM
  • Faulty Instrument Cluster
  • Problems with the Engine Control Module (ECM)
  • Malfunctioning CAN bus system
  • Software or firmware issues in the BCM
  • Other module communication failures
  • Grounding issues in the electrical system

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: 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 damaged

  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 BCM communicates over the Controller Area Network (CAN) bus. Check for continuity and proper resistance in the CAN bus wiring

  7. 7. Termination Resistors

    Ensure that the CAN bus has the correct termination resistors in place. A missing or faulty resistor can cause communication issues

  8. 8. Check for Short Circuits

    Use a multimeter to check for short circuits in the wiring harness that could affect communication between the BCM and other modules

  9. 9. Scan for Module Communication

    Use a scan tool to check if other modules on the CAN bus are communicating properly. If other modules are also showing communication issues, the problem may be with the bus itself rather than the BCM

  10. 10. Inspect for Environmental Factors

    Check for any environmental factors that could affect the BCM, such as water intrusion or extreme temperatures

  11. 11. Reset the System

    Clear the trouble codes using the OBD-II scanner and see if the code returns. Sometimes, a temporary glitch can cause communication issues

  12. 12. Update Software/Firmware

    If applicable, check if there are any software updates available for the BCM or the vehicle’s control modules. Sometimes, manufacturers release updates to fix communication issues

  13. 13. Consult Technical Service Bulletins (TSBs)

    Look for any TSBs related to the specific make and model of the vehicle. Manufacturers may have documented common issues and fixes for the U1852 code.1

  14. 14. Professional Diagnosis

    If the issue persists after performing the above steps, consider seeking help from a professional mechanic or dealership with experience in diagnosing BCM and communication issues. By following these steps, you should be able to identify the root cause of the U1852 code and take appropriate action to resolve the issue