Case IH 3683-02 - UCM – UCM: Vehicle controller loss of communication with steering wheel angle sensor

The control module is no longer receiving the expected data signals (usually via the CAN bus or a direct analog/digital circuit) from the sensor that monitors the physical position and rotation of the steering wheel.

• MAGNUM AFS Connect
• Steiger AFS Connect
• Puma

1. 1

   Inspect the wiring harness between the steering wheel angle sensor and the UCM for open circuits, chafed wires, or short circuits (e.g., CAN-low or CAN-high communication lines).

2. 2

   Disconnect the sensor and check the connector pins for corrosion, moisture, or pushed-back terminals. Verify that the sensor is receiving proper power and ground.

3. 3

   Inspect the steering column and the sensor mounting for excessive physical play, which can cause erratic readings or sensor disconnects.

4. 4

   Attempt to recalibrate the steering wheel angle sensor via the AFS Pro display or the Electronic Service Tool (EST). If calibration fails immediately, the sensor or harness is definitively at fault.

1. 1

   Prep the Machine

   Park the tractor on a level surface, center the steering wheels manually, turn off the engine, and disconnect the battery to prevent electrical spikes.

2. 2

   Access the Sensor

   Remove the steering column shrouds/covers. Depending on the specific cab configuration, you may need to remove the steering wheel to slide the sensor off the steering shaft.

3. 3

   Remove the Faulty Sensor

   Disconnect the electrical pigtail/connector from the steering wheel angle sensor. Unbolt the sensor retaining screws and remove the unit.

4. 4

   Install the New Sensor

   Slide the new steering wheel angle sensor into place, ensuring it is properly aligned with the steering shaft keyway (the wheels must remain perfectly centered during this step). Secure the mounting hardware.

5. 5

   Reassembly

   Reconnect the electrical harness, reinstall the steering column covers, and reattach the steering wheel (if removed). Reconnect the battery.

6. 6

   Mandatory Calibration

   Connect the CNH Electronic Service Tool (EST) or navigate to the Steering Settings menu on the AFS Pro display to perform a steering wheel angle sensor calibration. The system must learn the new sensor's exact center position.