Case IH 15329 – Steering Controller Module (SCM) or AST (Auxiliary Steering / Auto Steer) controller: Wheel Angle Sensor - CAN signal exceeds calibration limit.

The steering controller is receiving a signal from the Wheel Angle Sensor (WAS) that falls outside of its calibrated parameters. This typically happens if the wheels have been forced past their calibrated maximum angle, the sensor's physical mounting has shifted, the linkage is damaged, or the sensor has internally failed and lost its calibration.

• Steiger T4B
• Puma Series (e.g., 115, 125, 140, 155, 165, 180, 195, 210)
• Magnum Series (including AFS Connect Magnum)
• Steiger and Quadtrac Series (including AFS Connect Steiger/Quadtrac)
• Maxxum Series
• Farmall Series (e.g., 40-50 CVT)

1. 1

   Visual Inspection: Inspect the Wheel Angle Sensor mounted on the steering axle. Check for loose mounting brackets, bent linkage rods, or physical damage to the sensor body. For good steering performance, the WAS block must be solidly mounted.

2. 2

   System Log Check: Access the system log on your display (e.g., Pro 1200 or Ag Leader SteerCommand). Look for a 'Curvature bias warning' or similar message, which indicates that the sensor's current measurement has drifted from the calibrated measurement.

3. 3

   Verify Sensor Integrity: Check the diagnostic screen to verify that the raw WAS counts are within specification and balanced (you should see equal counts when turned fully left and fully right of center).

4. 4

   Wiring and Connections: Inspect the WAS cable and CAN bus connections for corrosion, damage, or loose pins.

1. 1

   Repair Physical Damage

   If the WAS bracket or linkage rod is bent or loose, repair or replace the damaged components and tighten all fasteners.

2. 2

   Replace Sensor (if faulty)

   If the sensor is internally damaged or fails to provide consistent raw counts during the diagnostic check, replace the Wheel Angle Sensor.

3. 3

   Perform Wheel Angle Sensor Calibration

   Turn on the tractor and access the ISObus diagnostic page or steering calibration page on the display (e.g., Pro 1200). Select the Wheel Angle Sensor calibration procedure. Turn the steering wheel to the maximum left position, drive forward slightly, and save the value. Turn the steering wheel to the maximum right position and save the value. Align the wheels straight ahead, drive forward a few centimeters to ensure they are perfectly straight, and save the center position.

4. 4

   Perform Steering Valve Calibration

   Follow the display prompts to calibrate the steering valve. This ensures the controller knows the exact hydraulic flow required to turn the wheels.

5. 5

   Perform Roll Calibration

   If required by your specific auto-guidance system, complete a roll calibration to ensure accurate cross-track error calculation.

6. 6

   Clear Fault Codes

   Clear the 15329 fault code and test drive the tractor in auto-steer mode to verify the repair.