John Deere 520529.12 – Front Chassis Module (SCO): Loader Boom Position Sensor Issue

This code indicates a fault with the signal coming from the front loader's boom position sensor. The controller is receiving an erratic, out-of-range, or missing signal from the sensor.

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

1. 1

   Inspect the loader boom position sensor for physical damage and check the mechanical linkage connecting the sensor arm to the loader frame to ensure it isn't bent, disconnected, or seized.

2. 2

   Inspect the wiring harness routing from the sensor back to the Front Chassis Module (SCO) for chafed wires, pinched harnesses, or corrosion inside the sensor connector.

3. 3

   Using John Deere Service ADVISOR or the in-cab diagnostic monitor, monitor the live voltage/percentage of the boom position sensor while raising and lowering the boom slowly. The signal should sweep smoothly without dropping to 0V, spiking to 5V, or having dead spots.

4. 4

   Attempt to run the Front Loader Boom Position Sensor Calibration procedure to rule out calibration issues.

1. 1

   Preparation

   Park the tractor on a level surface, lower the loader boom completely to the ground to relieve hydraulic pressure, turn off the engine, and disconnect the battery.

2. 2

   Removal

   Locate the boom position sensor on the loader linkage. Disconnect the wiring harness connector.

3. 3

   Dismounting

   Remove the retaining bolts holding the sensor body to the mounting bracket. Carefully detach the sensor's rotary arm from the mechanical linkage.

4. 4

   Installation

   Mount the new sensor to the bracket and reattach the mechanical linkage. Ensure the sensor is installed in the correct orientation so that the full range of boom motion does not over-extend the sensor's rotational limit.

5. 5

   Reconnection

   Plug the electrical connector back in and reconnect the tractor's battery.

6. 6

   Calibration

   Connect John Deere Service ADVISOR (or use the tractor's display monitor) to perform the Front Loader Boom Position Sensor Calibration. Follow the on-screen prompts to set the upper and lower boom limits.

7. 7

   Testing

   Clear the 520529.12 fault code. Operate the loader to verify that the Return-to-Position and Electronic Self-Levelling features function correctly.