Case IH F-103-01 - ECU – Engine ECU: Turbocharger speed sensor voltage is lower than expected

The engine controller is receiving a voltage signal from the turbo speed sensor that falls below the minimum calibrated threshold, typically pointing to a short to ground, a severed wire, or an internally failed sensor.

• MAGNUM AFS Connect
• Case IH Magnum AFS Connect series tractors
• Case IH 240 Series Axial-Flow Combines
• Steiger
• Puma
• Optum

1. 1

   Visual Inspection: Inspect the wiring harness and connectors between the turbo speed sensor (located on the turbocharger center section) and the Engine ECU. Look for chafed wires, melted insulation, or corroded connector pins.

2. 2

   Resistance Test: Disconnect the sensor and measure the resistance across its two signal wires using a multimeter. A healthy turbo speed sensor typically measures between 600 and 1200 ohms. If the resistance is out of this range, the sensor is internally faulty.

3. 3

   Voltage Supply Check: Turn the key ON and check the supply voltage to the sensor connector. Ensure it is receiving the correct reference voltage (typically +12V or +5V depending on the specific engine harness).

4. 4

   Pulse/Signal Test: If the wiring is intact, you can test the sensor's output by measuring the speed pulses between the tractor ground and the sensor signal pin while cranking the engine. The pulses should fluctuate between 0V and battery voltage. If no pulses are detected, the sensor is dead.

1. 1

   Power Down

   Turn off the machine and disconnect the negative battery cable to prevent electrical spikes.

2. 2

   Locate the Sensor

   Locate the turbocharger speed sensor, which is mounted directly into the center housing (CHRA) of the turbocharger.

3. 3

   Disconnect

   Unplug the electrical connector from the sensor.

4. 4

   Remove

   Remove the retaining bolt or screw holding the sensor in the turbo housing. Carefully pull the sensor straight out.

5. 5

   Inspect

   Look at the tip of the old sensor. If it shows signs of physical impact, the turbocharger compressor wheel may have excessive shaft play and could be failing.

6. 6

   Install

   Lubricate the O-ring on the new sensor with a small amount of clean engine oil. Push the new sensor into the housing and tighten the retaining bolt.

7. 7

   Reconnect

   Plug the electrical connector back in, ensuring it clicks and locks securely.

8. 8

   Clear Codes

   Reconnect the battery. Turn the key ON and use the AFS Pro display or a diagnostic scan tool to clear the inactive F-103-01 fault code. Start the engine and verify the code does not return.