Case IH 4044 – UCM (Universal Control Module) or Instrument Cluster (IC) / Master Controller: Hydraulic Oil Temperature Sensor Open Circuit

The control module is detecting infinite or abnormally high resistance on the sensor's circuit, typically caused by a broken wire, a disconnected harness plug, or a sensor that has failed internally.

• skid steer
• SSL (Skid Steer Loaders)
• CTL (Compact Track Loaders)
• Steiger
• Magnum
• Maxxum
• AFX8010

1. 1

   Perform a visual inspection of the hydraulic oil temperature sensor connector for corrosion, pushed-out pins, or a loose connection.

2. 2

   Trace the wiring harness from the sensor back to the UCM/Instrument Cluster, looking for chafing, pinched wires, or breaks (especially inside the steering column or along chassis pivot points).

3. 3

   Perform a resistance test on the sensor: a healthy sensor reads around 2,500 ohms at room temperature. If it reads 'OL' or infinite resistance, the sensor has failed internally.

4. 4

   Perform a voltage reference test: with the key ON (engine off), probe the harness side of the connector for a 5V reference signal. No voltage indicates a broken wiring harness.

1. 1

   Preparation

   Park the machine on a level surface, lower all hydraulic implements to the ground, and turn off the engine. Relieve any residual hydraulic pressure by cycling the hydraulic controls.

2. 2

   Locate the Sensor

   Find the hydraulic oil temperature sensor on the hydraulic reservoir or pump inlet manifold.

3. 3

   Disconnect

   Unplug the electrical harness connector from the sensor.

4. 4

   Fluid Catch

   Place a clean catch pan directly underneath the sensor to catch any hydraulic fluid that escapes during removal.

5. 5

   Removal

   Use a deep socket or wrench to unthread the faulty sensor from the manifold/tank.

6. 6

   Installation

   Inspect the threads of the new sensor. If it does not have pre-applied thread sealant, apply a hydraulic-safe liquid thread sealant (do not use Teflon tape, as shreds can contaminate the hydraulic system). Thread the new sensor in by hand, then tighten to OEM torque specifications.

7. 7

   Reconnection

   Plug the electrical harness back into the sensor, ensuring the locking tab clicks securely into place.

8. 8

   Fluid Check

   Check the hydraulic fluid level and top off any oil that was lost during the swap.

9. 9

   Clear Codes

   Turn the key to the ON position. Use the machine's diagnostic menu or a Case IH Electronic Service Tool (EST) to clear the inactive 4044 fault code. Start the machine and allow the hydraulic oil to reach operating temperature to verify the code does not return.