BCU 523745.31 – S100 HMS Plus Program Selector Switch, Fault. John Deere System Advisory.

BCU 523745.31 (BCU )

Code: 523745.31



Error code BCU 523745.31 is triggered when the Basic Control Unit (BCU) of a John Deere vehicle detects an unrealistic value from the HMS Plus program selector switch. This diagnostic trouble code indicates that the switch may be malfunctioning or that there is a problem within the circuit that transmits the switch’s position to the BCU, potentially due to issues like a faulty switch, poor wiring connections, or a disruption in the signal path.


The incorrect readings from the program selector switch could lead to improper functioning of the HMS Plus system, which is designed to enhance machine efficiency by automating certain functions. This fault may affect the system’s ability to correctly execute programmed tasks, reducing operational precision and potentially impacting overall productivity.


  • Inspect the HMS Plus Selector Switch and Wiring: Check the selector switch for physical damage or signs of wear that could affect its function. Examine the wiring and connections for any loose, corroded, or damaged components that might be interfering with signal transmission.
  • Test Electrical Continuity and Signal Integrity: Use a multimeter to test the electrical continuity of the switch circuit and the integrity of the signal being transmitted to the BCU. This will help determine if the issue is electrical in nature.
  • Replace or Repair Faulty Components: If the switch or any part of its circuit is found to be defective, replace or repair these components to ensure proper functionality. Ensure all connections are secure and properly insulated.
  • Re-calibrate or Reset the HMS Plus System: After addressing any hardware issues, recalibrate or reset the HMS Plus system to ensure it recognizes the correct input from the newly repaired or replaced selector switch.
  • Reset the BCU: Clear any diagnostic trouble codes and reset the BCU to ensure that it accurately processes inputs from the HMS Plus system post-repair.
  • Operational Testing: Conduct tests to verify that the HMS Plus program selector switch operates correctly and that the system responds appropriately to its settings.
  • Regular Maintenance and System Checks: Implement a routine inspection and maintenance schedule for the electrical and control systems, including the HMS Plus system, to prevent recurrence of similar issues.


Ensuring the integrity and functionality of control systems like the HMS Plus is vital for maintaining the high efficiency and operational effectiveness of agricultural machinery. Regular checks and prompt repairs of control components are essential to sustain optimal performance and reliability of the equipment. These practices help in minimizing downtime and maximizing the productivity of the machinery in demanding agricultural operations.