Case IH 3007 (F-4076-03) – Engine Control Unit (ECU): Engine coolant temperature sensor voltage is higher than expected (Signal Above Range Max)

This fault indicates that the voltage signal returning from the engine coolant temperature sensor to the controller is exceeding the maximum allowable threshold. This is typically caused by an open circuit in the sensor wiring, a short circuit to a high-voltage source (such as the battery), or a completely failed sensor.

• VESTRUM CVX
• Steiger Series (350–620 hp)
• Magnum Series (235–340, MX215–MX305)
• Maxxum Series
• Axial-Flow 240 Series
• 7230
• 8230
• 9230
• 5140
• 6140
• 7140
• Austoft 9900
• Patriot Sprayers (4420, SPX4410)
• Titan Floaters

1. 1

   Verify if the fault is currently active. If the fault is inactive, inspect the engine cooling system for an actual over-temperature condition (check for coolant leaks, radiator damage, or blockages).

2. 2

   Start the engine, run it at 2000 RPM, and check the battery voltage on the instrument cluster to ensure the alternator is not overcharging the system, which can skew sensor voltages.

3. 3

   Disconnect the coolant temperature sensor and measure its internal resistance with a multimeter. At 20°C (68°F), the resistance should be approximately 2.5 kOhms. If it reads open (infinite resistance) or significantly out of range, the sensor is faulty.

4. 4

   Inspect the wiring harness between the ECU and the coolant temperature sensor. Look for rubbed-through wires causing a short to battery voltage (+V) or a broken wire causing an open circuit.

1. 1

   Power Down

   Turn off the machine and disconnect the battery ground cable to prevent electrical spikes during repair.

2. 2

   Locate the Sensor

   Locate the engine coolant temperature sensor on the engine block/thermostat housing (refer to your specific engine's layout, e.g., FPT Cursor).

3. 3

   Inspect the Connector

   Unplug the sensor connector. Check for water intrusion, corrosion, or pushed-back pins. Clean the contacts with electrical contact cleaner if necessary.

4. 4

   Test the Circuit

   With the sensor unplugged, turn the key to the ON position (engine off). Use a multimeter to check the reference voltage at the harness connector (typically 5V). Check the ground circuit for continuity to the chassis/ECU ground.

5. 5

   Replace the Sensor

   If the wiring tests good but the sensor failed the resistance test (or if the fault persists after cleaning the connector), remove the old sensor. Have a catch pan ready, as some coolant may escape.

6. 6

   Install the New Sensor

   Thread the new OEM coolant temperature sensor into the housing. Torque to the manufacturer's specification.

7. 7

   Reassemble and Clear Codes

   Reconnect the electrical harness and the battery. Top off any lost coolant. Turn the key on, clear the inactive fault codes via the diagnostic menu, and start the engine to verify the code does not return.