John Deere 1079 – Header Control Unit: Height Sensor Power Voltage Too High

The voltage supplied to the height sensor power circuit is greater than 5.25 volts DC, which exceeds the acceptable range. This over-voltage condition is logged by the Header Control Unit (HCU) and affects the power supply to critical sensors involved in header operation. It is typically caused by a short circuit in the wiring harness connecting the HCU to the sensors, or a faulty internal voltage regulator within the Header Control Unit itself.

• 9450
• 9550
• 9560
• 9650
• 9660
• 9750
• 9760
• S-Series
• 70 Series STS
• 600 Series
• 600FD
• 615F
• 618F
• 620F
• 622F
• 625F
• 630F
• 635F
• 616R
• 618R
• 620R
• 622R
• 625R
• 630R
• 635R
• 900 Series
• corn heads
• 9650 STS
• 9750 STS
• 9860 STS
• 9650 CTS
• 700 Series

1. 1

   Verify the active fault code on the machine's display (often displayed as E01 1079 03).

2. 2

   Inspect the wiring harness between the Header Control Unit and all height sensors for chafing, corrosion, or short circuits, paying close attention to connection points at the feeder house.

3. 3

   Check sensor voltage using diagnostic address E01 15 to display the Height Sensor Power voltage (normal range is 4.8 to 5.2 volts). Individual sensor operating voltage should be between 0.5 and 4.5 volts.

4. 4

   Isolate the fault by disconnecting suspected sensors one at a time to see if the fault code disappears, which determines if the issue is in a specific sensor or the wiring.

1. 1

   Repair wiring harness

   If damage or a short circuit is found during inspection, repair or replace the affected wiring sections and ensure all connections are clean and secure.

2. 2

   Replace faulty height sensor

   If disconnecting a specific sensor clears the fault code, replace that sensor.

3. 3

   Replace Header Control Unit

   If the wiring and sensors are in good condition, the internal voltage regulator of the Header Control Unit is likely faulty. Replace the entire Header Control Unit.

4. 4

   Calibrate header system

   After replacing the Header Control Unit or any height sensors, perform a header calibration through the machine's display to ensure accurate header height functions.