BCU 002003.09 – Incorrect CAN Bus Message from EPC/TCU. John Deere System Advisory.

BCU 002003.09 (BCU 2003.09)

Code: 002003.09

Shortcode: 2003.09


Error code BCU 002003.09 is triggered when the Basic Control Unit (BCU) of a John Deere vehicle experiences data transfer issues with either the Electrically Powered Control (EPC) or the Transmission Control Unit (TCU). This diagnostic trouble code is set off due to intermittent or completely nonexistent reception of one or more CAN bus messages from these units. Potential causes for such disruptions include loose wiring connections, damaged cables, or faults within the CAN bus system itself, which can significantly impact the performance and operability of the vehicle.


Upon detection of these communication issues, the BCU may activate warning indicators on the vehicle’s dashboard to alert the operator. Depending on which messages are affected, this may influence the functioning of the vehicle’s transmission system or other electrically controlled components, leading to operational inefficiencies or safety concerns.


  • Inspect CAN Bus Connections: Begin by examining all wiring and connections associated with the CAN bus between the BCU and the EPC or TCU. Check for loose, corroded, or damaged connectors and wires.
  • Test CAN Bus Communication: Utilize diagnostic tools to test the integrity and continuity of communication between the BCU, EPC, and TCU. This testing can help pinpoint specific areas or components where signal loss or errors occur.
  • Repair or Replace Defective Wiring: Address any issues found during the inspection by repairing or replacing wires or connectors. This ensures that all electrical connections are secure and capable of transmitting data correctly.
  • Verify EPC and TCU Functionality: Ensure that both the EPC and TCU are functioning correctly and not contributing to the problem by sending corrupt or incorrect data.
  • Reset the BCU and Clear Diagnostic Codes: After making the necessary corrections, reset the BCU to clear any fault codes and reinitialize the system settings. This step helps to confirm that all systems are communicating properly without further interruptions.
  • Monitor System Operation: Following the repair and reset, closely monitor the system to ensure stable and consistent communication. Pay attention to the vehicle’s performance to confirm that all systems are responsive and operating as expected.


Robust and reliable communication between the BCU, EPC, and TCU is crucial for maintaining the operational integrity and safety of John Deere vehicles. Regular maintenance and proactive troubleshooting of the CAN bus system and related electronic components are essential practices to prevent potential failures and ensure continued efficient operation. Addressing CAN bus communication issues quickly minimizes downtime and helps maintain operational efficiency and vehicle safety.