Case IH U81 – Transmission Control Module (Transmission ECU): No signal from flywheel torque sensor

The control module is not receiving the expected rotational speed or torque data from the flywheel speed sensor. This signal is critical for calculating transmission input torque, balancing deceleration forces, and executing automated power-shift transmission modulation.

• Maxxum
• MXM Series (MXM120, MXM130, MXM140, MXM155, MXM175, MXM190)
• Maxxum Series
• Puma Series (140-240 CVX)
• Steiger Series
• Optum Series

1. 1

   Verify that the flywheel speed sensor is actually fitted to the transmission housing cover or flywheel bell housing.

2. 2

   Inspect the speed sensor's electrical connection and wiring harness for open circuits, shorts to ground, or loose pins.

3. 3

   Use the tractor's H-Menu/switch diagnostics (specifically H9 in the transmission module) to see if engine speed is being detected at all.

4. 4

   During the Auto Calibration Procedure, check the calculated distance from the edge of the flywheel lug to the damper disc finger to see if the processor is registering a physical reading.

1. 1

   Locate sensor

   Locate the flywheel speed sensor on the transmission housing cover or flywheel bell housing.

2. 2

   Disconnect sensor

   Disconnect the electrical connector (2-pin plug) from the sensor.

3. 3

   Remove sensor

   Remove the retaining screw/bolt holding the sensor in place and detach the faulty flywheel speed sensor.

4. 4

   Install new sensor

   Install the new inductive magnetic proximity speed sensor and secure it with the retaining screw.

5. 5

   Reconnect harness

   Reconnect the electrical harness.

6. 6

   Calibrate transmission

   Clear the fault codes and perform a transmission calibration (specifically the flywheel torque sensor calibration) to ensure the new sensor is recognized and the 4-5 synchronizer shifts correctly.