AIC 521133.08 – CommandQuad™ Range Switch B Fault. John Deere AIC System Alert.

AIC 521133.08 (AIC )

Code: 521133.08



This error code signifies a malfunction with the CommandQuad™ range switch B, where the switch appears to be stuck in the pressed position. This mechanical or electrical fault prevents the switch from returning to its neutral, unpressed state, leading to erroneous signals being sent to the transmission system.


As a precautionary measure to prevent incorrect transmission actions and potential mechanical damage, the control unit has placed the vehicle in a recoverable PARK position.


  • Physically inspect range switch B to determine if it is indeed stuck. Look for signs of mechanical obstruction, excessive wear, or damage that might prevent the switch from releasing properly.
  • Manually adjust the switch to see if it can be moved back to the unpressed position. If it remains stuck, further mechanical intervention may be required.
  • Test the switch’s electrical functionality using diagnostic tools to ensure it correctly registers the ON and OFF positions without overlap or interference.
  • Check all related wiring and electrical connections for potential issues such as shorts or loose connections that could affect the switch’s operation.
  • If the switch remains faulty despite attempts to free it or correct minor issues, replace it. Ensure the new switch is correctly installed and integrated into the system.
  • Once repairs or replacements are complete, recalibrate the switch settings and test the entire transmission system to ensure that all functions related to range switch B are fully operational and that the vehicle can exit the PARK position safely.


Regular maintenance of mechanical switches and their electrical components is crucial for the smooth operation of CommandQuad™ transmissions. Preventative inspections and immediate repairs of any faults help avoid operational delays and maintain the machinery in optimal working condition.