BCU 523704.15 – B20 Left Draft Sensor, Voltage Too High. John Deere System Advisory.

BCU 523704.15 (BCU )

Code: 523704.15



Error code BCU 523704.15 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 exceeds 4.75 volts. This diagnostic trouble code indicates a malfunction within the draft sensor circuit, potentially caused by issues such as electrical interference, a faulty sensor, or improper wiring that is resulting in elevated voltage levels.


The high voltage detection may lead to incorrect readings from the left draft sensor, affecting the tractor’s hitch control system. This could compromise 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 wiring for any signs of damage, wear, or loose connections that could be causing the high voltage readings.
  • Test Sensor Voltage: Utilize a multimeter to measure the voltage at the draft sensor’s input during operation to confirm the high voltage condition.
  • Replace or Repair Faulty Components: If the sensor or any part of its wiring is found to be faulty, undertake repairs or replace the damaged parts to ensure the integrity of the draft sensor circuit.
  • Re-calibrate the Draft Sensor: After repairing or replacing the necessary components, 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 repaired system and reinitializes its settings.
  • Test the System Functionality: Conduct tests to verify that the draft sensor operates correctly post-repair, ensuring that it no longer exhibits high voltage readings during operation.
  • Regular System Checks and Preventive Maintenance: Implement a routine inspection schedule for the electrical system, focusing on areas prone to wear and damage. Regular maintenance can prevent future issues and ensure the reliability of critical operational components like the draft sensor.


Proper sensor function is critical for precision agricultural operations that rely on accurate data inputs for effective machinery control. Regular maintenance and timely intervention when issues are detected are essential to prevent disruptions and ensure continued efficient operation of equipment. Ensuring that sensors and their connections are in good working condition through regular maintenance and timely repairs is key to maximizing the efficiency and reliability of the equipment.