Case IH 15272 – Steering Valve Controller: Wheel angle sensor crosscheck between the steering valve main and safety controllers failed.

The primary wheel angle sensor cross-check reading between the main controller and the safety controller (which is internal to the electronic steering valve) has deviated by greater than 10% for a period lasting longer than 100 milliseconds. This mismatch triggers a safety fault in the auto-guidance/steering system.

• Steiger T4B
• Stage V MR models
• Farmall
• Maxxum
• Puma
• Optum
• Magnum
• Steiger/STX series
• Patriot Sprayers (3230, 3320, 3330, 4420)
• Axial-Flow Combines

1. 1

   Inspect the wheel angle sensor (WAS) linkage and mounting bracket on the steering axle for excessive mechanical backlash, loose hardware, or bent arms causing erratic sensor readings.

2. 2

   Trace the 3-pin Deutsch/WP connector from the wheel angle sensor to the steering valve controller. Look for pinched wires, corrosion, or moisture in the connectors that could cause a voltage mismatch.

3. 3

   Check for related codes (15273, 15274, or 15275) which would point to a broader harness or controller failure rather than just the WAS.

4. 4

   Attempt to recalibrate the system by navigating to the ISObus diagnostic page on the Pro 1200 or AFS Pro 700 display and performing the Wheel Angle Sensor and Steering Valve calibration.

1. 1

   Turn off the tractor, engage the parking brake, and locate the wheel angle sensor on the steering axle.

2. 2

   Disconnect the 3-pin wiring harness connector from the sensor.

3. 3

   Remove the retaining ring and mounting bolts holding the sensor body and linkage arm.

   Typically 10-24x1/2 slotted washer head hex screws.

4. 4

   Remove the faulty wheel angle sensor and its O-rings.

5. 5

   Install the new wheel angle sensor.

   Crucial Fitment Note: Ensure the sensor is oriented correctly. If the sensor is assembled 180 degrees out of phase, it will provide inverted feedback, causing the machine to steer in figure-eights.

6. 6

   Reconnect the linkage arm and the 3-pin wiring harness.

7. 7

   Replace the entire electrohydraulic steering valve assembly if the sensor replacement does not clear the crosscheck fault.

   This indicates the safety controller internal to the electronic steering valve has failed.

8. 8

   Turn on the tractor, start up the guidance system, and navigate to the ISObus diagnostic page to perform a mandatory Wheel Angle Sensor and Steering Valve calibration.