Case IH 520228-02 - VCM – VCM: Steering valve controller communication fault with wheel angle sensor

The system detects an implausible relationship or communication breakdown between the steering valve controller and the wheel angle sensor (WAS). When the steering valve commands hydraulic flow to turn the wheels, the wheel angle sensor is either not reporting the expected physical movement, or the signal is erratic/missing. This mismatch triggers a safety fault in the automated steering system.

• MAGNUM AFS Connect
• Case IH Magnum series (including AFS Connect models)
• Case IH Steiger / Quadtrac series
• Case IH Puma and Optum series
• Case IH 8250 and similar flagship combines

1. 1

   Inspect the wiring harness between the Wheel Angle Sensor, the steering valve controller, and the VCM for chafing, corrosion, or loose pins

2. 2

   Inspect the physical linkage of the wheel angle sensor on the steering axle to ensure it is not bent, disconnected, or packed with debris

3. 3

   Perform a sensor sweep test using a multimeter to test the wheel angle sensor's output voltage lock-to-lock, watching for a smooth voltage sweep without dropouts or dead spots

4. 4

   Check if the steering valve spool is sticking or if there is an internal failure in the valve controller preventing it from moving the wheels as commanded

5. 5

   On newer combines and tractors, check the internal steering cylinder sensor if applicable

1. 1

   Repair Wiring

   If any damaged wires or corroded connectors are found during the diagnostic phase, repair or replace the affected harness sections.

2. 2

   Replace Faulty Components

   If the wheel angle sensor fails the sweep test or is physically broken, replace the sensor. If the sensor is internal to the steering cylinder and has failed, replace the steering cylinder assembly. If the steering valve is internally failed or sticking, replace the steering valve.

3. 3

   Bleed the Hydraulic System

   If the steering valve or cylinder was replaced, bleed the steering system. With the engine running, rotate the steering wheel about 10 times fully clockwise and 10 times fully counterclockwise at a normal, steady speed to purge air from the lines.

4. 4

   System Calibration

   After replacing the sensor or valve, you must perform a Wheel Angle Sensor and Steering Valve calibration. This is typically done through the AFS Pro 700 / 1200 display or using a dealer diagnostic tool (like the Case IH EST or Jaltest).

5. 5

   Test Drive

   Clear the stored fault codes in the VCM. Operate the steering system under normal field conditions to verify smooth, responsive control and ensure the code does not return.