Case IH F73 – Transmission Controller (TCU / EDC): Transmission Mid Speed Sensor Open Circuit

The control module is not detecting a continuous electrical path to the transmission's mid speed sensor, which typically means there is a severed wire, an unplugged connector, or the internal coil of the sensor itself has failed and broken the circuit.

• MXM
• MXM Series
• MXM 120
• MXM 130
• MXM 140
• MXM 155
• MXM 175
• MXM 190
• Maxxum series
• Puma series

1. 1

   Visually inspect the wiring harness leading to the mid speed sensor for chafing, rodent damage, or pinched wires.

2. 2

   Disconnect the sensor plug and inspect the pins for corrosion, dirt, or pushed-back terminals, then reconnect firmly.

3. 3

   Test the sensor for continuity using a multimeter; infinite resistance indicates a failed internal winding.

4. 4

   If the sensor tests good, check the wiring harness between the sensor and the Transmission Controller for an open circuit.

5. 5

   Ensure the sensor has not backed out of its mounting hole, causing improper clearance to the internal gear teeth.

1. 1

   Preparation

   Park the tractor on a level surface, engage the parking brake, turn off the engine, and block the wheels.

2. 2

   Removal

   Disconnect the electrical connector from the faulty mid speed sensor. Remove the retaining bolt holding the sensor to the transmission housing and carefully pull the sensor out.

3. 3

   Cleaning

   Thoroughly clean the mounting port and surrounding area to prevent dirt from falling into the transmission.

4. 4

   Installation

   Insert the new speed sensor. Secure it with the retaining bolt and reconnect the electrical harness.

5. 5

   Transmission Calibration

   Hold the High and Low range buttons and start the engine. 'CAL' will appear on the transmission display. Release the buttons. Set the engine speed to 1200 RPM (±100). Follow the on-screen prompts to cycle through the clutch pack calibrations until complete.