John Deere 174.04 – Engine Control Unit (ECU): Fuel Temperature Low Signal Voltage (ECU)

The Engine Control Unit (ECU) has detected that the input voltage from the fuel temperature sensor has dropped below the sensor's low voltage specification (typically below 0.1 V). This usually indicates that the sensor or its wiring has a short to ground, or the sensor itself has failed internally.

• 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
• 8R Series
• 8RT Series
• 9230
• 9330
• 9430
• 9530
• 9630
• 310G
• 310J
• 410J
• 710G
• 135D
• 450D LC
• 444J
• 544J
• 624J
• 850J
• 9570 STS
• 9860 STS
• CTS Combines

1. 1

   Inspect the fuel temperature sensor, its connector, and the wiring harness leading back to the ECU for chafing, bare wires, or corrosion that could cause a short to ground.

2. 2

   Disconnect the sensor and turn the key on. Back-probe the connector to verify if the ECU is supplying the correct reference voltage to the sensor.

3. 3

   Measure the resistance (ohms) across the sensor terminals. If the resistance is out of specification or shows continuity to ground, the sensor is internally shorted.

4. 4

   Check the signal wire for continuity to ground. If the wire is grounded while disconnected from the sensor, the wiring harness is pinched or shorted and needs repair.

1. 1

   Locate sensor

   Turn off the machine and locate the fuel temperature sensor on the engine's fuel delivery system (often near the fuel filter housing or injection pump).

2. 2

   Disconnect sensor

   Disconnect the electrical connector from the sensor.

3. 3

   Repair wiring

   Based on the diagnostic checks, if the wiring harness is damaged, repair the short to ground in the harness.

4. 4

   Remove faulty sensor

   If the wiring and ECU voltage are good, the sensor is faulty. Unthread the old fuel temperature sensor from the housing (have a rag ready to catch minor fuel spillage).

5. 5

   Install new sensor

   Install the new OEM fuel temperature sensor and tighten to the manufacturer's torque specification.

6. 6

   Reconnect harness

   Reconnect the electrical harness, ensuring the connector clicks securely into place.

7. 7

   Clear fault code

   Turn the key to the ON position and use a diagnostic service tool (like John Deere Service ADVISOR) or the machine's onboard monitor to clear the stored 000174.04 / SPN 174 FMI 4 fault code.

8. 8

   Verify repair

   Start the engine and verify that the code does not return and that the fuel temperature reads accurately.