John Deere 1536 – HCU: Center Stubble Height Sensor Voltage Too Low

The Center Stubble Height Sensor (also known as the Center HEADERTRAK Sensor) is reporting a voltage that has dropped below the acceptable minimum threshold of 0.5 VDC. This condition indicates a fault with the sensor itself or an issue with the associated wiring, which directly affects the Active Header Height Control (AHHC) system's ability to maintain proper header positioning.

• STS Combines
• 9570
• 9670
• 9770
• 9650
• 9750
• 9660
• 9760
• S-Series Combines

1. 1

   Visually inspect the wiring harness leading to all header height sensors for any signs of damage, corrosion, or loose connections

2. 2

   Access the combine's diagnostic menu to view live voltage readings from the header height sensors to confirm the center sensor is reading below 0.5V

3. 3

   Inspect the sensor components for physical damage, ensuring the linkage and pivot points are free of debris, well-lubricated, and able to move freely

4. 4

   Perform a header calibration to see if the sensor is simply out of adjustment (a failed calibration strongly indicates a failed or improperly set sensor)

1. 1

   Prepare machine for service

   Park the combine on a level surface, set the parking brake, and turn off the engine. Engage all safety locks for the header and reel.

2. 2

   Replace the sensor

   Locate the center stubble height sensor mounted on the header frame near the middle of the header, connected to the cutterbar via a linkage. Disconnect the wiring plug, unbolt the sensor assembly to remove it, and install the new sensor in the reverse order.

3. 3

   Initiate header calibration

   Navigate to the calibration menu on the combine's diagnostic display (e.g., CommandCenter) and select the header calibration option.

4. 4

   Set minimum and maximum heights

   Follow the prompts to lower the header completely to establish the minimum sensor setting (H-dn). Next, raise the header to its maximum height to establish the maximum sensor setting (H-UP).

5. 5

   Save calibration

   Save the calibration values so the system recognizes the new sensor and its operating range.