BCU 523745.31 – Unrealistic Value from HMS Plus Program Selector Switch. John Deere System Advisory.

BCU 523745.31 (BCU )

Code: 523745.31



The diagnostic trouble code BCU 523745.31 is issued when the Body Control Unit (BCU) detects an unrealistic value from the HMS Plus program selector switch. This fault indicates that the switch is outputting data that does not correspond to the expected parameters, potentially due to a malfunction within the switch mechanism or interference affecting its signal.


The BCU may temporarily disable the functions controlled by the HMS Plus program selector switch to prevent incorrect operations or further system complications. This can affect the performance of systems that rely on the accurate selection of operating modes.


  • Inspect the Selector Switch: Check the HMS Plus program selector switch for physical damage, signs of wear, or contamination that might interfere with its operation.
  • Test Switch Output: Use diagnostic tools to measure the output from the selector switch. Verify that the values it provides correspond to the positions or settings it is supposed to represent.
  • Replace Faulty Switch: If the switch is found to be defective, replace it to ensure correct functionality.
  • Check Wiring and Connections: Examine all associated wiring and connectors for loose connections or damage that might result in erratic signals.
  • Reset the System: After repairs or replacements, reset the BCU to clear the fault code and test the system to ensure that the switch is functioning correctly and the realistic values are being registered.


Regular maintenance and checks of input devices like selector switches are crucial to ensuring reliable operation of agricultural machinery. Faults in such components can lead to improper functioning of critical systems, affecting overall efficiency and safety. Immediate attention to and resolution of such issues help maintain the precision and reliability of machinery operations.