BCU 000639.14 – Very High Error Rate on Vehicle CAN Bus. John Deere System Advisory.

BCU 000639.14 (BCU 639.14)

Code: 000639.14

Shortcode: 639.14


Error code BCU 000639.14 occurs when the Basic Control Unit (BCU) of a John Deere vehicle detects a very high error rate in the Controller Area Network (CAN) Bus messages or identifies severe issues with the general connectivity of the vehicle CAN Bus. This diagnostic trouble code points to significant communication disruptions that could be due to faulty connections, corrupted data transmissions, or extensive electrical interference, potentially leading to major operational problems and safety concerns.


In response to this critical level of communication errors, the BCU might limit or shut down certain vehicle functions as a safety precaution, and initiate alerts to inform the operator of the severe system malfunction.


  • Comprehensive CAN Bus Inspection: Conduct a thorough inspection of the CAN Bus system, including all connectors, wiring, and network nodes. Look for physical damage, signs of wear, or improper installations that could contribute to signal loss or corruption.
  • Advanced Diagnostic Monitoring: Utilize advanced diagnostic tools to analyze CAN Bus traffic and pinpoint specific sources or patterns of errors. This step is crucial for identifying whether the issue is localized or system-wide.
  • Eliminate Electrical Interference: Check for and address any sources of electrical interference that could be affecting the CAN Bus. This may involve adjusting the layout of wiring, enhancing shielding on cables, or isolating CAN Bus components from high-interference devices.
  • Update or Reconfigure System Software: Ensure that all electronic control units (ECUs) on the CAN Bus are operating with compatible and updated software versions. Misconfiguration or software incompatibilities can exacerbate error rates.
  • Replace Defective Hardware: If diagnostics reveal that certain hardware components of the CAN Bus are defective, replace these components immediately to prevent further communication failures.
  • System Reset and Full Functional Testing: After addressing the hardware and software issues, reset the entire CAN Bus system and clear any stored error codes. Perform comprehensive functional tests under various operational scenarios to ensure that the very high error rate has been resolved and that the system is stable.


Given the critical role of the CAN Bus in vehicle operations, maintaining its reliability through regular checks and immediate attention to any error alerts is vital. Ensuring robust and error-free communication across the vehicle’s network is essential for the safe and efficient functioning of all integrated systems. Timely identification and correction of CAN Bus issues are imperative to avoid operational disruptions and ensure long-term vehicle performance and safety.