John Deere 110.03 – ECU: Engine Coolant Temperature Sensor Input Voltage High

The control unit is receiving a voltage signal from the Engine Coolant Temperature (ECT) sensor that is above the normal specification (typically greater than 4.9 Volts), indicating an open circuit, a disconnected sensor plug, or a completely failed sensor.

• 5085E
• 5090E
• 5090EL
• 5100E
• 5065M
• 5075M
• 5085M
• 5100M
• 5100MH
• 5100ML
• 5115ML
• 5095M
• 5095MH
• 5105M
• 5015ML
• 5090M
• 5115M
• 6110M
• 6120M
• 6130M
• 6145M
• 6155M
• 6175M
• 6195M
• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 5M Series
• 6R Series
• 7R Series
• 8R Series
• 9R Series
• 8020 Series
• 8120
• 8520
• 9560 STS
• 9660 STS
• S-Series
• T-Series
• W-Series
• 333E
• 240
• 250
• 260
• 270
• 280
• loaders
• excavators
• 4050
• 4450
• 8450
• R4038
• R4045

1. 1

   Check Coolant Levels: Ensure the radiator and coolant reservoir are filled to the proper levels.

2. 2

   Visual Wiring Inspection: Inspect the wiring harness leading to the ECT sensor. Look for broken wires, rubbed-through insulation, or a disconnected plug.

3. 3

   Connector Check: Unplug the sensor and check for corrosion, dirt, or moisture inside the connector pins.

4. 4

   Circuit Test: Use a multimeter to check for an open circuit or a short to a high-voltage source in the sensor wiring harness.

1. 1

   Safety First

   Do not attempt this repair while the engine is hot. Wait for the engine to cool completely to avoid severe burns from pressurized, boiling coolant.

2. 2

   Locate the Sensor

   The ECT sensor is typically threaded into the engine block or thermostat housing. On many John Deere engines, it is located right below the coolant reservoir on the upper right-hand side of the engine.

3. 3

   Prepare for Spillage

   Place a catch pan under the engine. You will lose a small amount of antifreeze when the sensor is removed.

4. 4

   Remove the Sensor

   Disconnect the electrical pigtail harness. Use a wrench or deep socket to unthread the old sensor from the block.

5. 5

   Install the New Sensor

   Thread the new OEM sensor into the port and tighten it to the manufacturer's torque specification.

6. 6

   Reconnect

   Plug the electrical harness back into the new sensor.

7. 7

   Refill Coolant

   Top off the engine coolant reservoir to replace any fluid lost during the swap.

8. 8

   Clear Codes

   Turn the key on and use the machine's diagnostic monitor or a scan tool to clear the stored 000110.03 fault code. Start the engine and verify the code does not return and the cooling fan operates normally.