John Deere 1534 – HCU: Left Stubble Height Sensor Voltage Too Low

The Header Control Unit (HCU) has detected that the voltage from the left stubble height sensor is below the minimum acceptable threshold of 0.5 VDC. The normal operating range for Active Header Height Control (AHHC) sensors is between 0.5 and 4.5 volts. A reading below this range indicates a potential failure of the sensor device itself, or an issue with the wiring and electrical connections.

• S550
• S660
• S670
• S670HM
• S680
• S680HM
• S690
• S690HM
• 9560 STS
• 9570 STS
• 9650 STS
• 9660 STS
• 9670 STS
• 9760 STS
• 9770 STS
• 9860 STS
• 9870 STS
• 600 Series Headers
• 700 Series Headers
• 615F
• 615R
• 616F
• 616R
• 618F
• 618R
• 620F
• 620R
• 622F
• 622R
• 625F
• 625R
• 630F
• 630R
• 635F
• 635R

1. 1

   Visually inspect the left stubble height sensor, linkage, and wiring for physical damage, corrosion, or bent components. Ensure the sensor arm and linkage move freely without binding.

2. 2

   Examine the wiring harness leading to the sensor for frayed wires or damage. Disconnect the sensor's electrical connector and check for corrosion, dirt, or moisture. Clean and tighten as needed.

3. 3

   Using a multimeter, check the voltage at the sensor connector. The voltage should be between 0.5 and 4.5 volts; a reading below 0.5 volts confirms the fault condition.

4. 4

   Attempt to run the header calibration procedure through the combine's display to see if it fails and provides additional diagnostic information.

1. 1

   Power Down the Machine

   Turn off the combine and disconnect the battery to ensure safety during the repair.

2. 2

   Locate the Sensor

   The left stubble height sensor is typically located on the left side of the header, near the skid plates or on the header frame.

3. 3

   Disconnect the Sensor

   Disconnect the wiring harness from the faulty sensor.

4. 4

   Remove the Old Sensor

   Unbolt and remove the old sensor from its mounting bracket.

5. 5

   Install the New Sensor

   Mount the new sensor, ensuring it is correctly aligned and securely fastened.

6. 6

   Reconnect Wiring

   Reconnect the wiring harness to the new sensor, ensuring a secure connection.

7. 7

   Calibrate the System

   After replacing the sensor, it is crucial to calibrate the header height control system. Follow the calibration instructions in the operator's manual for your specific combine and header.

8. 8

   Test the System

   Start the combine and test the auto header height control to verify that the system is functioning correctly.