Case IH 12637 – ABS ECU or Central Controller: Rear right wheel speed sensor - wheel diameter incorrect

The control module is receiving a signal frequency from the rear right wheel speed sensor that does not mathematically align with the expected rotational speed for the programmed wheel/tire diameter.

1. 1

   Verify the physical tire size on the rear right wheel matches the other tires and the dimensions programmed into the tractor's ECU.

2. 2

   Check the wheel speed sensor wiring for a short to ground or an open circuit.

3. 3

   Inspect the sensor for physical damage or debris that could disrupt the hall-effect signal frequency.

1. 1

   Verify ECU settings

   Access the tractor's ECU settings via the diagnostic interface to verify the programmed wheel diameter matches the physical tires installed.

2. 2

   Disconnect sensor harness

   If the tire sizes are correct and match, disconnect the rear right wheel speed sensor harness.

3. 3

   Test harness continuity

   Test the harness for continuity back to the ABS ECU.

4. 4

   Replace sensor

   If the wiring is intact, replace the faulty rear right wheel speed sensor.

5. 5

   Clear codes and test drive

   Clear the fault codes and perform a test drive to verify the ECU is receiving the correct frequency.