Case IH F-103-00 - ECU – Engine Control Module (ECM / Engine ECU): Turbo charger speed sensor voltage is higher than expected

The voltage signal returning from the turbocharger speed sensor to the controller is higher than the expected normal operating range, indicating a circuit shorted to a high source or a failure within the sensor itself.

• MAGNUM AFS Connect
• 240 Series Axial-Flow Combines
• 7240
• 8240
• 9240

1. 1

   Inspect the turbocharger speed sensor, its connector, and the engine wiring harness for visible damage, melting, or chafing.

2. 2

   Using a multimeter, test the sensor's signal wire for a short to a high source (e.g., shorted to battery voltage or a 5V reference line).

3. 3

   Disconnect the sensor and the Engine ECU harness connectors to check for pushed-out pins, moisture, or corrosion on the sensor supply and return pins.

4. 4

   Turn the key ON (engine off) and verify that the sensor is receiving the correct reference voltage and has a solid ground/return path to the ECM.

1. 1

   Power Down

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

2. 2

   Isolate the Fault

   Disconnect the turbocharger speed sensor. If a multimeter test confirms the wiring harness is shorted to a power source, locate the chafe or melt point in the harness and repair the wiring.

3. 3

   Replace the Sensor

   If the wiring harness tests good (no shorts to high voltage, good continuity), the sensor itself has failed internally. Remove the mounting bolt securing the speed sensor to the turbocharger compressor housing and pull the sensor out.

4. 4

   Install New Sensor

   Lubricate the O-ring on the new sensor, insert it into the turbocharger, and torque the hold-down bolt to OEM specifications.

5. 5

   Clear Codes

   Reconnect the battery, turn the key ON, and use the diagnostic screen/ICDU to clear the active DTC 1C38.

6. 6

   Test Run

   Start the engine. Note that if the machine was previously in an emergency power-loss state, it may need to be commanded to low idle before normal operation resumes.