Case IH 6912-02 - DEC – Transmission Control Unit (TCU): Transmission hydro motor speed sensor data is erratic, intermittent, or incorrect

The sensor is transmitting an invalid, unstable, or abnormal frequency signal regarding the hydrostatic motor's speed within the continuously variable transmission (CVT). This prevents the controller from accurately calculating vehicle speed and managing the proportional pump displacement.

• MAGNUM AFS Connect
• Case IH Magnum CVT
• T8.275
• T8.300
• T8.330
• T8.360
• T8.390
• T8.420

1. 1

   Check the physical setting and mounting of the hydro motor speed sensor on the transmission housing

2. 2

   Inspect the 2-pole female electrical connector and the associated wiring harness for corrosion, backed-out pins, or chafing

3. 3

   Test the sensor cables for continuity, open circuits, or shorts to ground/power

4. 4

   Restart the vehicle to determine if the intermittent error is a hard fault or a temporary glitch

1. 1

   Safety First

   Park the tractor on a level surface, engage the parking brake, and disconnect the batteries prior to performing any work to prevent accidental short circuits.

2. 2

   Gain Access

   Locate the hydro motor speed sensor on the CVT transmission assembly. You may need to remove the transmission access cover (secured by M8 x 1.25 x 16mm bolts) to reach the sensor.

3. 3

   Disconnect

   Unplug the 2-pole female wire connector from the hydro motor speed sensor.

4. 4

   Remove Sensor

   Unbolt and carefully extract the faulty speed sensor from the hydrostatic motor housing.

5. 5

   Install New Sensor

   Insert the replacement sensor, ensuring it is seated properly and fastened to the correct torque specifications.

6. 6

   Reassemble

   Reconnect the electrical connector. Reinstall the access cover and tighten the bolts.

7. 7

   Finalize

   Reconnect the battery. Connect a diagnostic tool to clear the 6912-02 fault code, then test drive the tractor in both forward and reverse to verify that the ground drive functions normally and the code does not return.