John Deere 520529.03 – Front Chassis Module (SCO): Loader Boom Position Sensor Signal Voltage High

The controller is receiving a voltage signal from the loader boom position sensor that exceeds the maximum expected threshold. This is typically caused by an open circuit (such as a broken ground wire), a short to a higher voltage source on the signal wire, or an internal failure of the sensor itself.

• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R

1. 1

   Inspect the wiring harness routing from the loader boom pivot area down to the Front Chassis Module (SCO) for pinch points, chafing, or severed wires.

2. 2

   Disconnect the boom position sensor and check for water intrusion, corrosion, or pushed-back pins inside the connector.

3. 3

   Test the sensor ground wire for continuity to the chassis/module ground (an open ground is the most common cause of a Voltage High fault).

4. 4

   With the sensor disconnected and the key ON, check the signal wire with a multimeter to ensure it is not shorted to a 12V power source.

5. 5

   If the 5V reference, ground, and signal wires all test good from the module to the connector, the sensor has failed internally and must be replaced.

1. 1

   Preparation

   Lower the loader boom completely to the ground to relieve hydraulic pressure. Turn off the tractor and remove the key.

2. 2

   Removal

   Locate the Loader Boom Position Sensor (typically mounted at the main boom pivot pin or linkage). Disconnect the electrical harness. Remove the retaining bolts/screws and carefully slide the sensor off the pivot shaft.

3. 3

   Installation

   Install the new sensor onto the pivot, ensuring the alignment tangs or flats match the boom linkage. Secure the mounting hardware and plug in the electrical connector.

4. 4

   Calibration

   Use the tractor's CommandCenter display or John Deere Service ADVISOR to run the Front Loader Boom Position Sensor Calibration procedure, which will teach the module the new minimum and maximum voltage values for the boom's travel range.

5. 5

   Clear Codes

   Clear the 520529.03 code and cycle the loader through its full range of motion to verify the repair.