BCU 523704.17 – B20 Left Draft Sensor, Voltage Too Low. John Deere System Advisory.

BCU 523704.17 (BCU )

Code: 523704.17



Error code BCU 523704.17 is activated when the Basic Control Unit (BCU) of a John Deere vehicle detects that the voltage at the signal input of the left-hand (l.h.) draft sensor falls below 0.25 volts. This diagnostic trouble code indicates a malfunction within the draft sensor circuit, potentially caused by issues such as a poor connection, a break in the wiring, or a faulty sensor that is preventing adequate voltage from being delivered to the sensor.


The low voltage detection can lead to incorrect readings from the left draft sensor, potentially affecting the tractor’s hitch control system. This might impair the tractor’s ability to effectively manage implements attached to the hitch, impacting performance and operational efficiency.


  • Inspect the Left Draft Sensor and Wiring: Check the left draft sensor and its associated wiring for any signs of damage, disconnection, or wear that could cause low voltage readings. Look specifically for loose connections, corroded terminals, or broken wires.
  • Test Sensor Voltage: Use a multimeter to verify the voltage at the draft sensor’s input during operation to confirm the low voltage condition.
  • Repair or Replace Faulty Components: If any issues are found with the sensor or its wiring, undertake repairs or replace the faulty components to ensure the correct functioning of the draft sensor.
  • Re-calibrate the Draft Sensor: After making any necessary repairs or replacements, recalibrate the left draft sensor to ensure it provides accurate data to the BCU.
  • Reset the BCU: Clear any diagnostic trouble codes from the BCU and reset the system to ensure it recognizes the updates and operates with the correct settings.
  • Test the System Functionality: Conduct tests to confirm that the draft sensor now operates correctly, providing stable and accurate readings during operation.
  • Implement Regular System Maintenance: Establish a routine for inspecting and maintaining the draft sensor and its circuitry to prevent future issues. Regular checks can help detect early signs of malfunction, reducing repair costs and preventing operational disruptions.


Accurate sensor function is crucial for precision agricultural operations. Regular maintenance and timely intervention when issues are detected are essential to prevent disruptions and ensure continued efficient operation of equipment. Maintaining the integrity of sensor inputs through careful monitoring and maintenance is key to maximizing the performance and reliability of agricultural machinery.