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U1590 Lost Communication with the Body Control Module (BCM)

The OBD2 code U1590 indicates that there is a loss of communication between the vehicle's control module and the Body Control Module (BCM), which may affect various electrical functions and systems in the vehicle

Definition

The OBD2 code U1590 indicates that there is a loss of communication between the vehicle's control module and the Body Control Module (BCM), which may affect various electrical functions and systems in the vehicle

Common causes

  • Faulty Body Control Module (BCM)
  • Damaged wiring or connectors
  • Corroded terminals
  • Blown fuses
  • Poor ground connections
  • Software issues or programming errors
  • Faulty communication network (CAN bus issues)
  • 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 Powertrain Control Module (PCM)
  • Malfunctioning Instrument Cluster
  • Battery or charging system problems
  • Faulty fuses related to the BCM
  • Software or firmware issues in the BCM
  • Other module communication failures
  • Grounding issues in the electrical system

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 leading 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 at the BCM connector

  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. Test Communication Lines

    CAN Bus: If applicable, check the CAN bus lines for continuity and proper resistance. Use a multimeter to measure the resistance between the CAN High and CAN Low lines

  9. 9. Scan Tool Communication

    Attempt to communicate with the BCM using a scan tool. If communication is not established, it may indicate a problem with the BCM or the communication lines

  10. 10. Check for Interference

    Aftermarket Accessories: If any aftermarket accessories have been installed, they may interfere with the BCM's operation. Disconnect them temporarily to see if the issue resolves

  11. 11. Perform a Hard Reset

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

  12. 12. Consult Technical Service Bulletins (TSBs)

    Check for any TSBs related to the U1590 code for your specific vehicle make and model. Manufacturers may have issued guidance on common issues and fixes

  13. 13. Replace the BCM (if necessary)

    If all other troubleshooting steps fail and the BCM is determined to be faulty, consider replacing it. Ensure proper programming and configuration after replacement

  14. 14. Seek Professional Help

    If you are unable to resolve the issue, it may be best to consult a professional mechanic or dealership with experience in diagnosing and repairing BCM-related issues.Conclusion By following these steps, you can systematically diagnose the cause of the U1590 code. Always ensure safety precautions are taken when working with vehicle electronics, and consult your vehicle's service manual for specific details related to your make and model