BCU 002221.09 – Incorrect CAN Bus Message from PLC. John Deere System Advisory.

BCU 002221.09 (BCU 2221.09)

Code: 002221.09

Shortcode: 2221.09


Error code BCU 002221.09 is triggered when the Basic Control Unit (BCU) of a John Deere vehicle detects communication issues with the Programmable Logic Controller (PLC). This diagnostic trouble code indicates that the BCU is experiencing intermittent or nonexistent reception of one or more CAN bus messages from the PLC. Common causes for such disruptions could include loose wiring, faulty connections, or signal interference affecting the data transmission.


The BCU may respond to these communication failures by displaying warning indicators or by entering a safe mode to prevent potential malfunctions caused by the lack of reliable data from the PLC.


  • Inspect CAN Bus Wiring and Connections: Thoroughly check all connections and wiring associated with the CAN bus between the BCU and PLC. Look for any signs of damage, wear, or looseness that might be affecting signal transmission.
  • Test CAN Bus Communication: Utilize diagnostic tools to monitor and test the integrity of the communication link between the BCU and PLC. Identify any specific areas where interruptions or losses occur.
  • Repair or Replace Faulty Components: Make necessary repairs or replacements to any damaged wiring or connectors to ensure a stable and reliable connection.
  • Evaluate PLC Functionality: Ensure that the PLC itself is operating correctly and not sending erroneous data that could lead to miscommunication.
  • Reset the BCU and Clear Diagnostic Codes: After addressing any identified issues, reset the BCU to clear any stored error codes and to reestablish baseline system settings.
  • Monitor System Performance: Continue to monitor the system after making repairs to ensure that communication has been fully restored and is consistent. Verify that the transmission system operates correctly under various conditions.


Maintaining robust communication between the BCU and PLC is essential for the proper functioning of vehicle systems that rely on precise and accurate data exchanges. Regular system checks and maintenance can help prevent communication errors and ensure continuous and efficient operation of John Deere machinery. Addressing issues promptly when they arise minimizes downtime and maintains operational efficiency.