Case IH 12635 – TECU / ABS: Front right wheel speed sensor - damaged sensor ring

The control module is receiving an erratic, implausible, or missing signal from the front right wheel speed sensor. This indicates a mechanical issue with the sensor ring (tone ring), such as missing teeth, physical damage, or severe debris buildup that disrupts the magnetic pulse.

• Puma
• Optum
• Magnum
• Steiger
• T7
• T8
• T9

1. 1

   Visually inspect the front right sensor ring (tone ring) for physical damage, missing teeth, or heavy accumulation of mud, metal shavings, or debris.

2. 2

   Verify the air gap between the front right wheel speed sensor and the sensor ring. Check for a bent ring or loose wheel bearing causing gap fluctuations.

3. 3

   Inspect the front right wheel speed sensor wiring harness and connector for corrosion, moisture, or breaks. Test for 12V power (with ignition on) and continuity back to the TECU/ABS module.

4. 4

   Test the sensor itself; if the ring is intact, the sensor's magnetic pickup may have failed or shorted.

1. 1

   Prepare machine

   Park the tractor on a hard, level surface, engage the parking brake, and turn off the battery disconnect switch.

2. 2

   Lift axle

   Safely lift and support the front right axle using heavy-duty jack stands.

3. 3

   Remove wheel

   Remove the front right wheel to gain clear access to the hub and steering knuckle assembly.

4. 4

   Remove sensor

   Locate the front right wheel speed sensor. Disconnect its electrical connector and remove the retaining bolt to extract the sensor from the housing.

5. 5

   Inspect and access sensor ring

   Inspect the sensor ring. Depending on the specific front axle configuration (e.g., suspended vs. standard steer), you may need to remove the planetary gear cover and disassemble the wheel hub to fully access and remove the damaged sensor ring.

6. 6

   Replace sensor ring

   Remove the damaged sensor ring and carefully press the new sensor ring into place, ensuring it seats squarely.

7. 7

   Reassemble hub

   Reassemble the hub components to OEM torque specifications.

8. 8

   Install sensor

   Install the wheel speed sensor (it is highly recommended to use a new O-ring).

9. 9

   Reconnect wiring

   Reconnect the sensor wiring harness and secure it with cable ties to prevent rubbing.

10. 10

    Finalize and test

    Reinstall the wheel, lower the tractor, clear the fault code via the diagnostic menu, and perform a test drive to verify the TECU is reading the front right wheel speed correctly.