CAB 524021.31 – Left-Hand Reverser Lever Multiple Switch Circuit Fault

CAB 524021.31 (CAB )

Code: 524021.31



The error code CAB 524021.31 is activated when the CAB control unit detects simultaneous failures in two or more switches associated with the left-hand reverser (LHR) lever position. This failure can compromise the ability of the control unit to accurately determine the lever’s position, potentially leading to incorrect gear engagement and operational hazards.


In response to this detection of multiple switch failures, the control unit commands the vehicle into a ‘PARK’ position. This safety measure is designed to prevent unintended vehicle movement and can be recovered from once the underlying issue is resolved.


  • Inspect Reverser Lever Switches: Conduct a thorough examination of all switches involved in the LHR lever’s operation. Look for signs of physical damage, wear, or electrical failure.
  • Test Electrical Connectivity and Functionality: Using a multimeter or a specialized diagnostic tool, test each switch individually for continuity and proper functionality. This will help isolate any switches that are not performing as expected.
  • Replace Faulty Switches: If one or more switches are found to be defective, replace them to ensure reliable operation of the reverser lever system.
  • Verify Wiring and Connections: Check all associated wiring and connectors for any signs of corrosion, damage, or loose connections that might affect switch performance.
  • Reset and Recalibrate the System: After repairing or replacing the necessary components, reset the control unit to clear any fault codes. Recalibrate the system if necessary to ensure that all switches are correctly recognized and functioning.
  • Operational Testing: Test the functionality of the LHR lever under various conditions to confirm that the vehicle responds correctly to each position of the lever and that no further faults are detected.


Regular maintenance and timely diagnosis of switch and sensor issues are critical for the safe operation of vehicles equipped with complex control systems like the LHR lever. Ensuring that all position switches are functioning correctly helps prevent operational errors and enhances overall vehicle safety.

Control Units: John Deere

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