BCU 000186.15 – Rear PTO Speed Sensor Misreading. John Deere System Advisory.

BCU 000186.15 (BCU 186.15)

Code: 000186.15

Shortcode: 186.15


Error code BCU 000186.15 is initiated when the Basic Control Unit (BCU) of a John Deere vehicle detects a speed signal from the rear Power Take-Off (PTO) speed sensor, despite the rear PTO being switched off. This fault may indicate a sensor malfunction or an electrical issue causing erroneous signals. Additionally, this diagnostic trouble code may be triggered during the normal coasting down of an implement after the PTO has been disengaged, in which case it may not signify a fault.


Upon detecting this condition, the BCU may log the fault and alert the operator via the dashboard indicator, potentially leading to confusion or unnecessary checks if the signal is due to normal coast down.


  • Verify Operational Context: First, confirm whether the fault code was set under normal operational conditions, such as during the coasting down of an implement. If this is the case, reset the fault code and monitor to see if it reoccurs under different conditions.
  • Inspect PTO Speed Sensor and Wiring: Check the rear PTO speed sensor for any signs of damage or wear. Inspect the wiring for shorts or disconnections that might cause incorrect readings.
  • Test Sensor Accuracy: Use diagnostic tools to test the PTO speed sensor’s accuracy. Verify that the sensor stops sending speed data when the PTO is turned off and not just coasting down.
  • Check for Electrical Interference: Ensure that there is no electrical interference from other components affecting the sensor readings. This may involve inspecting other electrical systems located near the PTO speed sensor.
  • Replace Faulty Sensor: If diagnostics confirm a sensor malfunction when the PTO is genuinely off, replace the sensor to resolve the issue.
  • Reset the BCU and Perform System Check: After any necessary repairs or adjustments, reset the BCU to clear the diagnostic codes and perform a comprehensive system check to ensure no further issues are detected.


Regular maintenance and periodic checks of the PTO system and its sensors can help prevent false readings and ensure reliable operation of your machinery. Proper sensor function is crucial for the accurate operation of PTO-driven implements and overall vehicle efficiency. Addressing these issues promptly ensures that the PTO system maintains optimal performance and minimizes downtime for your John Deere equipment.