Case IH F-105-01 - ECU – Engine Controller / Engine ECU: Intake manifold temperature sensor voltage is lower than expected

The voltage signal returning from the intake manifold temperature sensor has fallen below the normal or expected operating range. This typically points to a short to ground in the sensor circuit, a failed sensor, or a wiring harness issue.

• MAGNUM AFS Connect
• MX Magnum Series Tractors
• TG Series Tractors
• Farmall Series Tractors (e.g., 105U, 115U, 105A)
• 240 Series Axial-Flow Combines
• 8800 Series Sugar Cane Harvesters

1. 1

   Inspect the wiring harness and the electrical plug for the intake manifold temperature sensor for chafing, moisture, or a short to ground.

2. 2

   Verify that the sensor is receiving a 5V reference supply from the ECU.

3. 3

   Measure the resistance of the sensor to ensure it scales according to ambient temperature. If resistance is lower than specified, there is an internal short.

4. 4

   Perform a jumper wire test by disconnecting the sensor and installing a jumper wire between the sensor signal terminal and the common ground terminal. If the code changes to 'Voltage Above Normal', the sensor has failed.

5. 5

   If the sensor and wiring test perfectly, test the system with a replacement ECU to rule out a faulty Engine Controller.

1. 1

   Turn off the machine and ensure the engine is cool.

2. 2

   Locate the intake manifold temperature sensor.

   It is typically mounted directly on the intake manifold or on the air cleaner outlet tube near the turbocharger elbow.

3. 3

   Remove any fan shields, harness retainers, or hose retainers on the side of the engine that may be blocking access to the sensor.

4. 4

   Disconnect the electrical plug for the intake manifold temperature sensor.

5. 5

   Unthread and remove the faulty sensor from the manifold.

6. 6

   Thread the new intake manifold temperature sensor into place and tighten to the specified torque.

7. 7

   Reconnect the electrical plug to the new sensor.

8. 8

   Reinstall any shields or retainers that were removed.

9. 9

   Power on the machine, clear the pending/active fault codes from the CAN system, and run the engine to verify the code does not return.