BCU 000084.02 – Wheel Speed Sensor Fault. John Deere System Advisory.

BCU 000084.02 (BCU 84.02)

Code: 000084.02

Shortcode: 84.02


The error code BCU 000084.02 indicates a problem with the B09/B35 wheel speed sensor on a John Deere vehicle. This diagnostic trouble code is triggered when the Basic Control Unit (BCU) detects either an open circuit or an invalid sensor signal, suggesting that the sensor is outside of its valid operational range. Such issues can arise due to sensor malfunction, wiring problems, or physical damage to the sensor or its environment.


Upon detection of this fault, the affected system’s functionality may be compromised, which can influence the performance and safety of the vehicle, especially in systems that rely on accurate wheel speed data such as traction control and anti-lock braking systems.


  • Inspect Sensor and Wiring: Check the B09/B35 wheel speed sensor for any signs of physical damage or wear. Inspect the wiring and connections for corrosion, breaks, or loose connections that might be causing an open circuit or signal disruptions.
  • Test Sensor Functionality: Use diagnostic tools to test the wheel speed sensor’s functionality. Ensure it is generating the correct signal and that the signal is reaching the BCU without interference.
  • Replace Faulty Sensor: If testing confirms the sensor is faulty, replace it with a new one to restore proper functionality.
  • Clear Diagnostic Codes: After repairs, clear any diagnostic trouble codes from the BCU and perform a road test to ensure the issue is fully resolved.
  • Regular Maintenance Checks: Include wheel speed sensors in regular vehicle maintenance checks to catch and mitigate potential issues before they lead to system faults.


Wheel speed sensors are critical for various vehicle safety and performance systems. Maintaining them in good working order is essential for ensuring the overall reliability and safety of the vehicle. Regular inspections and timely repairs of these sensors can prevent more significant issues down the road and help maintain the effectiveness of related systems like ABS and traction control.