John Deere 001872.03 – HCU or HCC: Front Hitch Position Sensor High Voltage

The system has detected an abnormally high voltage signal from the front hitch position sensor. The '.03' Failure Mode Identifier (FMI) signifies 'Voltage Above Normal, or Shorted to High Source'. This indicates an issue within the sensor's electrical circuit, most commonly pointing to an open circuit on the ground wire or a defective potentiometer sensor.

• 6R Series
• 6230R
• 6250R

1. 1

   Visually inspect the wiring harness and connectors between the front hitch position sensor and the control unit for damage, corrosion, or loose connections. Note that wiring on hitches can be susceptible to damage from hydraulic oil leaks, which can degrade the insulation and cause shorts.

2. 2

   With the key on, disconnect the sensor and check for a constant 5-volt supply at the sensor's connector to rule out a defective harness.

3. 3

   Check for an open ground circuit; a voltage reading of more than 4.75 volts on the ground circuit indicates an open wire.

4. 4

   Test the position sensor (potentiometer) with a multimeter set to Ohms. Measure the total resistance between the two outer terminals, then measure between the center terminal (wiper) and an outer terminal while manually moving the hitch. Look for smooth resistance changes without erratic jumps or dead spots.

1. 1

   Repair wiring harness

   If the wiring harness is found to be damaged, shorted, or has an open ground, repair the affected wires. Ensure all connections are clean and secure.

2. 2

   Replace position sensor

   If the sensor fails the resistance test or has dead spots, disconnect the wiring harness, remove the sensor from its mounting on the front hitch assembly, install the new sensor in the correct orientation, and reconnect the harness.

3. 3

   Perform hitch calibration

   After replacing the position sensor, perform a hitch calibration procedure to electronically teach the control unit the upper and lower limits of the hitch's movement. This may require a diagnostic tool or access to the tractor's command center, and often requires a specific engine RPM to complete successfully.