John Deere 1537 – HCU: Reel Fore/Aft Position Sensor or Deck Plate Position Sensor Voltage Too High

The Header Control Unit (HCU) detects that the voltage from the Reel Fore/Aft Position Sensor or the Deck Plate Position Sensor is exceeding the normal operating range of 4.5 VDC. This indicates a potential fault with the sensor itself, a wiring issue, or a mechanical linkage problem. It is classified as a priority 3 service alert, meaning it requires attention but may not immediately halt machine operation.

• 9450
• 9550
• 9650
• CTS Combines
• 90 Series Corn Heads
• 614R
• 615F
• 615R
• 616R
• 618F
• 618R
• 620F
• 620R
• 622F
• 622R
• 625D
• 625F
• 625R
• 630D
• 630F
• 630R
• 635D
• 635F
• 635R
• 640D

1. 1

   Inspect the wiring harness and connectors between the sensor and the Header Control Unit (HCU) for secure connections, damage, or corrosion.

2. 2

   Visually inspect the sensor arm and linkage for physical damage, bending, obstructions, or material buildup.

3. 3

   Check the mechanical components (reel carriage or deck plates) for binding, ensuring they move freely without interference or bent tie bars.

1. 1

   Adjust sensor linkage

   If the fault is related to the deck plate position sensor, shorten the linkage by approximately 5 mm (about 5 turns) to decrease the voltage. If the linkage is at its minimum length, reposition the adapter in the tie bar.

2. 2

   Perform sensor calibration

   Attach the header to the combine, connect the header harness, and start the combine. Recalibrate the sensor via the in-cab display. For deck plates (menu 'dEc'): fully close using the reel aft switch, then fully open using the reel fore switch, and save. For reel fore/aft: move the reel to its fully extended, lowered, raised, and retracted positions as prompted.

3. 3

   Replace the sensor

   If the fault code persists after linkage adjustment and calibration attempts, replace the faulty sensor and perform a new calibration.