Case IH 6912-01 - DEC – Transmission Control Module (TCM): Transmission hydro motor speed sensor data valid, below normal range - most severe.

The control module is receiving a valid, readable signal from the transmission's hydrostatic motor speed sensor, but the speed value being reported is critically below the expected normal operational range. This typically points to a failing sensor, a wiring/connector issue causing high resistance, or a mechanical issue where the hydro motor is physically under-speeding.

• MAGNUM AFS Connect
• Case IH Magnum CVT
• T8.275
• T8.300
• T8.330
• T8.360
• T8.385
• T8.390
• T8.420

1. 1

   Inspect the 2-pole female electrical connector (Part # 87695582) on the CVT top cover assembly for dirt, moisture, or corrosion, which can alter the sensor's voltage signal and cause a below normal range reading.

2. 2

   Check for related active pressure codes for Port 'A' or Port 'B' pressure sensors, or swash control solenoid faults. If the hydro pump is failing to generate pressure, the hydro motor will physically run slow, meaning the sensor is reading correctly and the mechanical drive is the actual issue.

3. 3

   Inspect the hydro motor speed sensor access cover (Part # 47624853) for signs of physical damage or severe fluid leaks that could compromise the sensor.

1. 1

   Clean the area

   Clean the area around the top of the CVT transmission housing to prevent debris from entering the hydrostatic circuit.

2. 2

   Remove access cover

   Locate and remove the Hydro Motor Speed Sensor Access Cover (OEM Part # 47624853).

3. 3

   Disconnect connector

   Disconnect the 2-pole female electrical connector (OEM Part # 87695582) from the speed sensor.

4. 4

   Extract sensor

   Unbolt and carefully extract the hydro motor speed sensor from the CVT top cover assembly.

5. 5

   Install new sensor

   Install the new hydro motor speed sensor and secure it with the retaining hardware.

6. 6

   Reconnect connector

   Reconnect the 2-pole electrical connector, ensuring it clicks securely into place.

7. 7

   Reinstall access cover

   Reinstall the access cover and torque the bolts to OEM spec.

8. 8

   Clear codes and test

   Clear the fault codes from the TCM and perform a test drive to ensure the hydro motor speed registers within the normal operational range.