Case IH 2379 – Transmission Control Module (TCM): Malfunction of the three-speed shaft speed sensor

The control unit is not receiving a valid RPM signal from the 3rd shaft speed sensor inside the transmission, which can cause shifting issues or cause the transmission to shift to neutral.

• Steiger T4B
• Case IH STX Steiger series
• Case IH Quadtrac series

1. 1

   Monitor live data in the transmission menu on the A-post display to see if the 3rd shaft RPM is reading zero, dropping out erratically, or matching the other shafts.

2. 2

   Inspect the wiring harness leading to the sensor on the lower left-hand side of the transmission for open circuits, short circuits to ground, or short circuits to the battery.

3. 3

   Check the sensor connectors to ensure they are fully seated, undamaged, and that the pins are tight and in the correct position.

4. 4

   Disconnect the sensor and the ECU to test the circuit for continuity. Repair the harness if damaged before condemning the sensor.

1. 1

   Locate the Sensor

   Sensor 3 is located on the lower left-hand side of the transmission towards the rear.

2. 2

   Clean the Area

   Thoroughly clean the area around the sensor on the transmission housing to prevent dirt from falling into the transmission.

3. 3

   Remove the Sensor

   Disconnect the electrical connector and unbolt the sensor from the transmission housing.

4. 4

   Retain the Spacer

   Remove the spacer from the old sensor and transfer it to the new sensor. The speed sensors often share the exact same part number, but use different spacers to set the correct sensor depth.

5. 5

   Install the New Sensor

   Insert the new sensor (with the correct spacer installed) into the transmission housing and tighten the mounting hardware.

6. 6

   Reconnect and Clear Codes

   Reconnect the electrical harness. Turn the key on, clear the inactive fault codes from the A-post monitor, and test drive the tractor to ensure the transmission shifts correctly and the code does not return.