Case IH 15233 - AST – MTA CCM & APH: Steering wheel sensor - communication lost

The control module has lost the data signal or communication feed from the steering wheel angle/position sensor. When this occurs, the machine's auto-guidance and steering feedback systems cannot determine the position or velocity of the steering wheel.

• MAXXUM T4E
• VESTRUM CVX
• Farmall 40
• Farmall 45
• Farmall 50
• Maxxum 115
• Maxxum 125
• Maxxum 135
• Maxxum 145
• Maxxum 150
• Magnum 180
• Magnum 200
• Magnum 220
• Magnum 240
• Magnum 310
• Magnum 340
• Puma 185
• Puma 200
• Puma 220
• Puma 240
• Steiger 370
• Steiger 420
• Steiger 470
• Steiger 500
• Steiger 540
• Steiger 580
• Steiger 620
• Optum
• Vestrum
• 7120 Combine

1. 1

   Harness & Wiring Inspection: Trace the wiring harness from the steering angle sensor (typically located on the steering cylinder or articulation joint) back to the main harness. Look for chafed wires, breaks, or pinch points.

2. 2

   Connector Check: Disconnect the sensor and inspect the pins for corrosion, moisture ingress, or backed-out terminals.

3. 3

   Voltage & Resistance Testing: Verify that the sensor is receiving its 5-volt reference signal and has a solid ground. Check the signal wire for continuity back to the CCM/APH module.

4. 4

   Fuse Inspection: Check the cab fuses related to the auto-steer/chassis control system, as a blown fuse can cause a complete loss of communication.

1. 1

   Power down and disconnect battery

   Power down the machine and disconnect the battery.

2. 2

   Locate steering angle sensor

   Locate the steering angle sensor. On most tractors and wheel loaders, it is an external sensor mounted on the front axle steering cylinder or articulation joint. (Note: On certain flagship combines like the 7120, the sensor may be built directly into the steering cylinder, requiring a different replacement approach).

3. 3

   Disconnect electrical harness

   Disconnect the electrical harness from the sensor.

4. 4

   Remove faulty sensor

   Unbolt the sensor linkage/mounting hardware and remove the faulty sensor.

5. 5

   Install new sensor

   Install the new steering angle sensor and secure the mounting bolts.

6. 6

   Reconnect electrical harness

   Reconnect the electrical harness, ensuring the weather-pack seal clicks into place.

7. 7

   Restore power

   Reconnect the battery and power on the machine.

8. 8

   Clear fault code

   Connect a diagnostic service tool to the machine to clear the 15233 fault code.

9. 9

   Calibrate sensor

   Crucial Step: Perform a steering angle sensor calibration via the diagnostic tool or in-cab monitor so the ECU can learn the new center, full-left, and full-right steering limits.