John Deere 90.03 – CCU (Central Control Unit) or RPT (Rear PTO Control Module): Transmission Hydraulic Oil Temperature Sensor High Voltage or Rear PTO Oil Temperature Sensor Circuit Voltage High

The control module is receiving a voltage signal from the temperature sensor that is higher than the normal operating range. In 5-volt reference sensor circuits, a "High Voltage" code almost always indicates an open circuit (such as a disconnected plug, a broken wire, or a completely failed internal sensor resistor) or a short to a high-voltage source.

• 5085M
• 5100M
• 5100MH
• 5100ML
• 5115ML
• 5045E
• 5055E
• 5065E
• 5075E
• 5085E
• 5090E
• 5100E
• 5075M
• 5095M
• 5105M
• 5115M
• 7185J
• 7195J
• 7205J
• 7210J
• 7225J
• 7720
• 7820
• 7920
• 7630
• 7730
• 7830
• 7930
• 9230
• 9330
• 9430
• 9530
• 9630
• 9470RT
• 9520RT
• 9570RT

1. 1

   Restart the tractor engine to acknowledge and reset the code, ruling out a temporary communication glitch

2. 2

   Inspect the wiring harness leading to the transmission/PTO hydraulic oil temperature sensor for chafed wires, rodent damage, or a disconnected plug

3. 3

   Disconnect the sensor and check the pins for corrosion, moisture intrusion, or pushed-back terminals

4. 4

   Access the CCU diagnostic addresses on the CommandCenter display to view the live hydraulic oil temperature sensor voltage

5. 5

   Operate the engine at 2200 RPM for 1–2 minutes to see if the code transitions from stored to active

1. 1

   Preparation

   Park the tractor on a level surface, engage the park brake, turn off the engine, and remove the key. Allow the transmission/hydraulic fluid to cool to avoid burns.

2. 2

   Locate the Sensor

   Locate the transmission hydraulic oil temperature sensor (or Rear PTO oil temperature sensor). Its exact location varies by model but is typically threaded directly into the side or lower half of the transmission housing or rear PTO housing.

3. 3

   Prepare for Fluid Loss

   Place a clean drain pan directly beneath the sensor, as removing it will allow hydraulic/transmission fluid to leak out.

4. 4

   Remove the Sensor

   Disconnect the 2-pin electrical connector. Use a deep socket or wrench to unthread the faulty sensor from the housing.

5. 5

   Install the New Sensor

   Ensure the new sensor has a new O-ring installed (if required by the specific part number). Thread the new sensor into the housing and tighten to OEM torque specifications.

6. 6

   Reassembly

   Reconnect the electrical harness, ensuring the locking tab clicks into place.

7. 7

   Fluid Check

   Check the transmission/hydraulic oil level dipstick or sight glass and top off any fluid lost during the swap.

8. 8

   Clear Codes

   Turn the key to the RUN position, clear the CCU 000090.03 code via the display monitor, and start the tractor to verify the repair.