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U1585 BCM Communication Failure

The OBD2 code U1585: BCM Communication Failure indicates a communication issue between the Body Control Module (BCM) and other modules in the vehicle's network, potentially affecting various electrical functions

Definition

The OBD2 code U1585: BCM Communication Failure indicates a communication issue between the Body Control Module (BCM) and other modules in the vehicle's network, potentially affecting various electrical functions

Common causes

  • Faulty Body Control Module (BCM)
  • Damaged wiring or connectors
  • Corroded terminals
  • Poor ground connections
  • Software issues or bugs in the BCM
  • Malfunctioning communication network (CAN bus)
  • Other module failures affecting communication
  • Battery voltage issues or low power supply

Common misdiagnoses

  • Faulty Body Control Module (BCM)
  • Wiring issues or shorts in the communication lines
  • Defective or corroded connectors
  • Malfunctioning Instrument Cluster
  • Issues with other control modules (e.g., PCM, ECM)
  • Battery or power supply problems
  • Software or firmware issues in the BCM
  • Grounding problems in the electrical system

Troubleshooting steps

  1. 1. Check for Additional Codes

    Use an OBD-II scanner to check for any other related trouble codes. This can provide more context about the issue and help identify if other modules are affected

  2. 2. Inspect Wiring and Connectors

  3. 3. Visually inspect the wiring and connectors related to the BCM and other modules in the communication network. Look for signs of damage, corrosion, or loose connections

  4. 4. Pay special attention to the ground connections, as poor grounding can lead to communication failures

  5. 5. Check for Short Circuits

  6. 6. Use a multimeter to check for short circuits in the wiring harness. A short to ground or power can disrupt communication between modules

  7. 7. Test the BCM

  8. 8. If the wiring and connectors appear to be in good condition, the BCM itself may be faulty. Testing the BCM may require specialized equipment or software

  9. 9. If possible, try swapping the BCM with a known good unit to see if the problem persists

  10. 10. Inspect Other Modules

  11. 11. Check other modules that communicate with the BCM. A failure in another module can sometimes cause communication issues

  12. 12. Ensure that all modules are functioning correctly and that their connections are secure

  13. 13. Check for Software Updates

  14. 14. Sometimes, communication issues can be resolved with a software update. Check with the manufacturer for any available updates for the BCM or other related modules

  15. 15. Clear Codes and Test Drive

  16. 16. After performing any repairs or inspections, clear the trouble codes and take the vehicle for a test drive to see if the code reappears

  17. 17. Consult Technical Service Bulletins (TSBs)

  18. 18. Look for any TSBs related to the U1585 code or BCM communication issues for your specific vehicle make and model. Manufacturers may have specific recommendations or known fixes

  19. 19. Professional Diagnosis

  20. 20. If the issue persists after performing the above steps, it may be necessary to seek professional help. A qualified technician can perform more advanced diagnostics and repairs. By following these steps, you can systematically identify and resolve the communication failure indicated by the U1585 code