AIC 521136.08 – CommandQuad™ Range Switch A Fault. John Deere AIC System Alert.

AIC 521136.08 (AIC )

Code: 521136.08



This error code indicates a malfunction with the CommandQuad™ transmission system’s range switch A, specifically that the switch may be stuck in the pressed position. Such a condition can interfere with the proper operation of the transmission by sending continuous, erroneous signals.


In response to this fault, the control unit has automatically placed the vehicle into a recoverable PARK position, temporarily disabling movement to prevent unintended actions and maintain safety.


  • Manually check the range switch A to determine if it is indeed stuck. Attempt to move it to the unpressed position to see if it can be freed.
  • Inspect the switch for any signs of physical damage, debris, or wear that might cause it to stick. Clean and lubricate the switch mechanism if needed to ensure smooth operation.
  • Test the switch with diagnostic tools to ensure it is functioning properly, with clear differentiation between ON and OFF positions.
  • Examine the electrical connections and wiring associated with the switch for any faults that might contribute to its malfunction, such as shorts or loose connections.
  • If the switch cannot be repaired or continues to malfunction, replace it. Ensure the new switch is properly calibrated and integrated into the vehicle’s control system.
  • After repairs or replacement, recalibrate the related systems if necessary and conduct tests to verify that the vehicle can safely exit the PARK position and that the switch operates correctly without sticking.


Regular maintenance of mechanical and electrical components like transmission range switches is crucial to the reliable operation of heavy machinery. Promptly addressing issues such as sticking or faulty switches helps prevent operational disruptions and maintains safety standards.