AIC 521128.31 – CommandQuad™ Range Switches Conflict. John Deere AIC System Alert.

AIC 521128.31 (AIC )

Code: 521128.31



This error code, AIC 521128.31, signals a conflict within the CommandQuad™ transmission system, specifically involving the range switch CDE. The fault is identified when multiple range switches are erroneously read as being pressed simultaneously, which can lead to incorrect gear selection signals and potentially unsafe transmission responses.


In response to this fault and to prevent any possible transmission damage or unintended vehicle movements, the control unit has automatically shifted the vehicle into a recoverable PARK position.


  • Thoroughly inspect the range switch CDE and adjacent switches to ensure they are not physically stuck or mechanically failing. Check for any signs of dirt, debris, or wear that could cause the switches to stick in a pressed position.
  • Test the functionality of each range switch individually using diagnostic equipment to verify that they are operating independently and not affecting each other’s state.
  • Check the electrical connections and wiring associated with the range switches for shorts, corrosion, or damage that could result in erroneous signals being sent to the control unit.
  • If a specific switch or multiple switches are found to be defective, replace them. Ensure that all new components are properly calibrated and tested for correct operation within the system.
  • After resolving the issue, recalibrate any necessary transmission settings and conduct extensive testing to confirm the vehicle can exit the PARK position safely and that all range switches function correctly without conflicts.


Maintaining the integrity and proper operation of transmission range switches is critical for vehicle safety and efficiency. Regular checks and prompt repairs are essential, particularly in environments where exposure to elements and frequent use could degrade switch performance more quickly. Ensuring that all mechanical and electrical components are functioning correctly helps prevent operational disruptions and extends the lifespan of the machinery.