WOMS
U code network High severity

U1855 Lost Communication with Body Control Module (BCM)"

The OBD2 code U1855 indicates that there is a communication failure between the vehicle's control modules, specifically indicating a lost connection with the Body Control Module (BCM)

Definition

The OBD2 code U1855 indicates that there is a communication failure between the vehicle's control modules, specifically indicating a lost connection with the Body Control Module (BCM)

Common causes

  • Faulty Body Control Module (BCM)
  • Damaged wiring or connectors
  • Corroded terminals
  • Poor ground connection
  • Faulty communication network (CAN bus issues)
  • Blown fuses
  • Software or firmware issues in the BCM
  • Intermittent electrical connections

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
  • Problems with other modules in the network
  • Software or firmware issues in the BCM
  • Battery or charging system problems
  • Grounding issues in the vehicle's 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 pushed back

  4. 4. Check Power and Ground

    Power Supply: Verify that the BCM is receiving the correct voltage. Use a multimeter to check the power supply to the BCM

  5. 5. Ground Connections

    Ensure that the ground connections for the BCM are secure and free of corrosion

  6. 6. Inspect the BCM

    Physical Condition: Check the BCM for any signs of physical damage or water intrusion

  7. 7. Reprogramming

    If the BCM has been replaced, ensure that it has been properly programmed to the vehicle

  8. 8. Check for Communication Issues

    CAN Bus Communication: Use a scan tool to check if other modules in the vehicle are communicating properly. If other modules are also not communicating, there may be a problem with the CAN bus

  9. 9. Network Integrity

    Inspect the CAN bus wiring for shorts, opens, or other issues

  10. 10. Test the BCM

    If possible, test the BCM in another vehicle of the same make and model to determine if the module is faulty

  11. 11. Alternatively, you can use a known good BCM to see if the issue resolves

  12. 12. Check for Software Updates

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

  13. 13. Clear Codes and Test Drive

    After performing the above checks and repairs, clear the codes using the OBD-II scanner and take the vehicle for a test drive to see if the code returns

  14. 14. Consult Technical Service Bulletins (TSBs)

    Look for any TSBs related to the U1855 code for your specific vehicle make and model. Manufacturers may have specific recommendations or known issues

  15. 15. Seek Professional Help

    If the issue persists after performing these steps, it may be necessary to consult a professional mechanic or an automotive technician with experience in electrical systems and BCM diagnostics. By following these steps, you should be able to identify the root cause of the U1855 code and take appropriate action to resolve the communication issue with the Body Control Module