Case IH F71 – Transmission Controller (TCU): Engine Torque/RPM Sensor Open Circuit

The controller has lost the electrical signal from the Engine Torque/RPM sensor, indicating a broken wire, unplugged connector, or internal sensor failure.

• MXM
• MXM 120
• MXM 130
• MXM 140
• MXM 155
• MXM 175
• MXM 190
• TM115
• TM120
• TM125
• TM130
• TM135
• TM140
• TM150
• TM155
• TM165
• TM175
• TM190

1. 1

   Inspect the 2-pin plug-and-play socket at the sensor for corrosion, backed-out pins, or moisture

2. 2

   Check the wiring harness between the sensor and the transmission controller for an open circuit (broken wire) or chafing

3. 3

   Ensure the Engine Torque/RPM sensor has not been accidentally swapped with the transmission mid-speed or output speed sensors during previous maintenance

4. 4

   If the wiring and connectors test good, suspect an internal failure of the sensor itself

1. 1

   Locate the Sensor

   The Engine Torque/RPM sensor is positioned on the transmission housing cover or flywheel bell housing, where it reads the rotational movement of the flywheel damper.

2. 2

   Disconnect and Inspect

   Unplug the sensor's 2-pin connector. Test the harness for continuity back to the transmission controller.

3. 3

   Replace the Sensor

   If the harness is intact, unthread the faulty inductive sensor from the housing and install the replacement.

4. 4

   Reconnect

   Plug the harness back into the new sensor.

5. 5

   Calibrate the Transmission

   Perform a Transmission/EDC Calibration. Ensure the tractor is between 20°C and 50°C. Apply the parking brake, turn off A/C, and deselect all electrical/hydraulic services. Enter the calibration mode (Mode HA) using the High and Low range buttons. Set engine speed to 1200 ERPM and follow the on-screen prompts until 'END' is displayed.