John Deere 520529.04 – Front Chassis Module (SCO): Loader Boom Position Sensor Signal Voltage Low

The voltage signal returning from the front loader's boom position sensor to the controller has dropped below the minimum acceptable threshold. This condition is typically caused by a short to ground in the signal wire, a loss of the 5V reference voltage, a disconnected harness, or an internal failure of the sensor itself.

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

1. 1

   Inspect the loader boom position sensor connector and the wiring harness routing down the loader frame for physical damage, pinched wires, or corrosion in the pins.

2. 2

   Disconnect the sensor and use a multimeter to check the harness side for a solid 5V reference signal and a good ground.

3. 3

   Check the signal wire between the sensor connector and the Front Chassis Module (SCO) for continuity, and ensure it is not shorted to ground.

4. 4

   While monitoring the voltage with a multimeter or John Deere Service Advisor, wiggle the harness near the sensor and pivot points to see if the voltage drops out, which would indicate an intermittent wiring break.

5. 5

   If power, ground, and signal wiring all test within specification, the sensor itself has failed internally and must be replaced.

1. 1

   Preparation

   Lower the loader boom to the ground to relieve hydraulic pressure and turn off the tractor key.

2. 2

   Removal

   Disconnect the electrical connector from the loader boom position sensor. Remove the mounting bolts/hardware securing the sensor to the loader frame pivot point and remove the faulty sensor.

3. 3

   Installation

   Mount the new position sensor in the exact orientation as the old one and secure the mounting hardware. Reconnect the electrical harness.

4. 4

   Calibration

   You must calibrate the new sensor. Use the tractor's monitor or John Deere Service Advisor to run the automated boom position sensor calibration routine.

5. 5

   Verification

   Clear the inactive 520529.04 code and cycle the loader boom through its full range of motion to ensure the code does not return.