BCU 523704.03 – B20 Left Draft Sensor, Voltage Too High During Calibration. John Deere System Advisory.

BCU 523704.03 (BCU )

Code: 523704.03



Error code BCU 523704.03 is triggered when the Basic Control Unit (BCU) of a John Deere vehicle detects a voltage exceeding 4.75 volts at the signal input of the left draft sensor during its calibration phase. This elevated voltage indicates a potential malfunction within the draft sensor circuit, which could be due to issues such as a faulty sensor, incorrect wiring, or an electrical interference causing the sensor to output higher than normal voltage levels.


The high voltage reading can result in inaccurate sensor readings, potentially affecting the tractor’s hitch control system. This might impair the tractor’s ability to manage implements accurately, impacting agricultural operations and the efficiency of the machinery.


  • Inspect the Left Draft Sensor and Associated Wiring: Check the left draft sensor and its wiring for any signs of damage, wear, or incorrect connections that could be causing the high voltage readings.
  • Measure Sensor Voltage: Utilize a multimeter to verify the voltage at the draft sensor’s input during calibration to confirm the high voltage condition.
  • Replace or Repair Faulty Components: If the sensor or any component of its circuitry is found to be faulty, replace or repair these parts to ensure proper functionality. Ensure all connections are secure and properly insulated.
  • Re-calibrate the Draft Sensor: After making 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 calibration.
  • 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.


Maintaining the integrity of sensor inputs is crucial for precision agricultural operations. Accurate calibration and functioning of draft sensors are essential for the effective use of hitch and implement control systems. Regular maintenance, timely repairs, and careful monitoring of these systems are key practices for sustaining the optimal performance and longevity of agricultural machinery.