Case IH 15234 - AST – AST / MTA CCM: Steering wheel sensor offline

The control module has lost communication with the steering wheel sensor (also known as the steering angle sensor) over the CAN bus network. Because the sensor is offline, the system cannot detect the steering wheel's position or velocity, which disables auto-guidance and related steering features.

• MAXXUM T4E
• VESTRUM CVX
• AFX8010
• 7010
• 7120
• 7230
• 8010
• 8120
• 8230
• 9010
• 9120
• 9230
• Farmall series (40-45-50)
• Maxxum series (100-140)
• Profi series
• 2WD/4WD tractor models (110 through 190)

1. 1

   Verify the code via the instrument cluster by navigating the 'H' menus to the R1 module, menu H3, and selecting the AST system to view active states.

2. 2

   Check power and ground to ensure the sensor is receiving the correct reference voltage and has a solid ground.

3. 3

   Inspect the CAN High and CAN Low lines between the steering wheel sensor and the AST controller for open circuits, short circuits, or high resistance.

4. 4

   Inspect the harness connector at the steering column or cylinder for pushed pins, corrosion, or moisture intrusion.

1. 1

   Power Down

   Turn off the machine and disconnect the battery to prevent electrical spikes.

2. 2

   Locate the Sensor

   Depending on the machine, locate the steering wheel sensor (typically mounted on the steering column for manual override detection or near the steering cylinder).

3. 3

   Test the Harness

   Disconnect the sensor. Using a multimeter, verify continuity on the CAN lines back to the AST module, and ensure 12V power and ground are present at the connector when the key is ON.

4. 4

   Replace the Sensor

   If the wiring harness tests good, the sensor's internal CAN transceiver has likely failed. Unbolt the defective steering wheel sensor and install the new OEM replacement.

5. 5

   Reassemble and Power Up

   Reconnect the sensor harness and the battery.

6. 6

   Calibrate

   Clear the inactive fault codes. A steering angle sensor calibration procedure must be carried out using the instrument cluster or the dealer diagnostic tool so the system learns the new sensor's center (0-degree) index point.