BCU 523704.03 – High Voltage Detected in Left Draft Sensor During Calibration. John Deere System Advisory.

BCU 523704.03 (BCU )

Code: 523704.03



Diagnostic trouble code BCU 523704.03 is generated when the basic control unit (BCU) detects a voltage at the signal input of the left draft sensor exceeding 4.75 volts during calibration. This high voltage reading typically indicates a malfunction within the draft sensor circuit, possibly caused by an electrical short, incorrect wiring, or a fault within the sensor itself.


The BCU may deactivate the sensor or related systems to prevent damage or inaccurate readings from affecting the operation of agricultural equipment, which relies on precise sensor data for optimal performance.


  • Inspect Wiring and Connections: Check the wiring and connectors associated with the left draft sensor for any signs of damage, corrosion, or incorrect connections that could result in high voltage readings.
  • Test the Sensor and Circuit: Use a multimeter or similar diagnostic tool to measure the voltage levels within the sensor circuit. Identify areas where voltage may be leaking or where shorts may have developed.
  • Replace or Repair Faulty Components: If specific components or sections of wiring are found to be faulty, replace or repair them to restore normal operation and voltage levels.
  • Re-calibrate the Sensor: After making necessary repairs, recalibrate the draft sensor to ensure it provides accurate and reliable readings.
  • Verify System Integration: Ensure that the sensor is correctly integrated into the overall system, with no additional factors or external influences affecting its performance.


Regular maintenance and calibration of sensors are essential for the efficient operation of agricultural equipment. Monitoring and maintaining proper voltage levels in sensor circuits is crucial for preventing malfunctions that could impact the accuracy and reliability of operations. Prompt attention to such issues helps maintain operational efficiency and extend the lifespan of the equipment.