Case IH U74 – Fast Steer Controller (KA module) or EPL / Transmission Control Module: LVDT Calibration Unsuccessful

The LVDT (Linear Variable Differential Transformer) calibration has been unsuccessful because the sensor readings were out of range after the 4th calibration attempt.

• Puma/Mid Range Magnum
• Case IH Puma Series
• Case IH Magnum Series
• Case IH Steiger Series

1. 1

   Check the LVDT sensor connection: Inspect the wiring harness, connector pins, and cables leading to the LVDT sensor for open circuits, short circuits, or corrosion.

2. 2

   Inspect the Fast Steer hydraulic valve assembly: Verify that the hydraulic valve has not been incorrectly assembled during previous maintenance, which can physically restrict the spool's movement.

3. 3

   Test the LVDT sensor: Check the sensor for internal failure or erratic resistance/voltage sweeps.

4. 4

   Check the Fast Steer hydraulic valve: Look for mechanical binding, sticking spools, or internal hydraulic leaks preventing the valve from reaching its full stroke during calibration.

1. 1

   Resolve Hardware Issues

   Repair any damaged wiring. If the wiring is intact but the sensor is failing, replace the LVDT sensor. If the valve spool is binding, replace the Fast Steer hydraulic valve assembly.

2. 2

   Prepare for Calibration

   Start the tractor and set the engine speed to 1300 RPM. Ensure the transmission oil is up to operating temperature (above 5°C / 41°F, though warmer is preferred).

3. 3

   Access the Service Menu

   Use the 'h', 'm', and 'dimming' buttons on the instrument cluster to navigate to the 'HH' service menus.

4. 4

   Navigate to the Fast Steer Controller

   Go to menu H1 and locate the fast steer symbol on the KA controller.

5. 5

   Select the Sensor

   Use the 'h' and 'm' buttons to toggle through the available options until the display shows 'Lvdt' (LVDT sensor).

6. 6

   Run the Calibration

   Press the 'dimming' button to select the LVDT option. Press the 'dimming' button again to activate the calibration. The system will automatically pilot the solenoid and measure the LVDT values in both directions to overwrite the default values. The lower central display will show a countdown from '5' as the calibration is performed. Once complete, clear the codes and test the steering system.