Case IH 15267 - AST – AST (Advanced Steering / Auto Steering): AST: Steering valve controller failure - LVDT frequency out of range

The LVDT (Linear Variable Differential Transformer) is an inductive sensor located inside the steering valve that measures the physical displacement (stroke) of the internal spool or pushed rod. This fault code indicates that the frequency signal being sent from the LVDT sensor to the steering controller is falling outside of the expected or calibrated operating range.

• MAXXUM T4E
• VESTRUM CVX
• Magnum
• Steiger
• Puma
• Maxxum
• Optum
• Farmall

1. 1

   Check the H-Menu Diagnostics by navigating to the R1 module, menu H3 (AST system) to view live data and confirm the active fault.

2. 2

   Inspect the wiring harness and connectors between the steering valve LVDT sensor and the AST controller for open circuits, short circuits, or corrosion.

3. 3

   Attempt to perform an AST steering calibration via the AFS Pro 700 display or the H-menu to see if the controller can relearn the LVDT sensor's center and end-of-stroke frequencies.

1. 1

   Power Down and Isolate

   Turn off the tractor and relieve hydraulic pressure from the steering circuit.

2. 2

   Inspect the Steering Valve

   Locate the steering valve assembly and the attached LVDT sensor.

3. 3

   Replace the Sensor/Valve

   If the wiring is intact but the LVDT frequency remains out of range (or the sensor has failed internally), the LVDT sensor must be replaced. Note: On many Case IH hydrostatic steering valves, the LVDT sensor is integrated into the valve, requiring the replacement of the entire steering valve assembly or the specific sensor cap.

4. 4

   Reassemble and Bleed

   Install the new sensor or steering valve assembly. Reconnect the hydraulic lines and bleed the steering system of air.

5. 5

   Recalibrate the AST System

   You must perform a steering sensor calibration (AST steering calibration) using the electronic service tool (EST) or the in-cab display (like the Pro 700) so the controller learns the new LVDT frequency range.

6. 6

   Clear Codes

   Clear the non-volatile memory (NVM) of the ECU to erase the inactive 15267 fault code.