John Deere 110.04 – ECU / CCU: Engine Coolant Temperature Sensor Signal Voltage Low

The control module is receiving a signal voltage from the Engine Coolant Temperature (ECT) sensor that is below the acceptable threshold (typically below 0.1 VDC), indicating a short circuit to ground in the sensor's wiring harness or an internal short within the sensor itself.

• 5065M
• 5075M
• 5085M
• 5095M
• 5095MH
• 5105M
• 5015ML
• 5090M
• 5100M
• 5100MH
• 5100ML
• 5115M
• 5085E
• 6110R
• 6155R
• 6215R
• 9230
• 9330
• 9430
• 9530
• 9630
• 9560 STS
• 9660 STS
• 9750 STS
• 204L
• 304L
• 444J
• 544J
• 624J
• 330LC-8B
• 450DLC
• 310SJ
• 410J

1. 1

   Check the engine coolant level and inspect the radiator for debris, as extreme overheating can sometimes trigger erratic sensor behavior.

2. 2

   Inspect the ECU/CCU connector and the ECT sensor connector for dirty, corroded, damaged, or poorly positioned terminals.

3. 3

   Perform a circuit isolation test (to check for an internal sensor short): Disconnect the pigtail connector from the coolant temperature sensor and check active codes. If the code changes from 110.04 to 110.03 (Voltage High / Open Circuit), the sensor is internally shorted and must be replaced.

4. 4

   Perform a wiring test (to check for a harness short): If the code remains 110.04 with the sensor unplugged, the fault lies in the wiring harness (a short to ground between the sensor connector and the ECU). Use a proper test kit like John Deere JT07328 to avoid damaging terminals.

1. 1

   Power Down

   Turn off the engine, remove the key, and allow the engine to cool to avoid burns from hot coolant.

2. 2

   Locate the Sensor

   Find the Engine Coolant Temperature Sensor, typically located on the engine block or near the thermostat housing.

3. 3

   Disconnect

   Unplug the wiring harness from the sensor.

4. 4

   Drain Coolant

   Depending on the sensor's mounting height, drain a small amount of coolant from the radiator to prevent a spill when the sensor is removed.

5. 5

   Remove and Replace

   Unscrew the faulty sensor. Install the new OEM replacement sensor and tighten it to the manufacturer's specifications.

6. 6

   Reconnect

   Plug the wiring harness back into the new sensor, ensuring the weather-pack seal clicks securely into place.

7. 7

   Refill and Test

   Top off the engine coolant. Start the engine, allow it to reach operating temperature, and verify via the dash or Service ADVISOR tool that the 000110.04 code has moved from 'Active' to 'Stored' (and can be cleared), and that the temperature gauge reads accurately.