Case IH 12632 – ABS Control Module or Frame ECU / Vehicle Control Module: Rear left wheel speed sensor - damaged sensor ring

The control module is receiving an erratic, implausible, or missing rotational speed signal from the rear left wheel, indicating that the sensor ring is physically damaged.

• Puma
• Magnum
• Steiger
• Maxxum
• Optum
• Patriot
• Axial-Flow

1. 1

   Monitor live wheel speed data for all four wheels using a diagnostic scanner to identify intermittent drops on the rear left wheel

2. 2

   Inspect the rear left sensor ring for cracks, missing teeth, or heavy rust

3. 3

   Check the magnetic tip of the wheel speed sensor and the ring for a buildup of metallic shavings or mud

4. 4

   Verify that the clearance (air gap) between the sensor tip and the tone ring is within OEM specifications

5. 5

   Inspect the sensor wiring harness for chafing or breaks to rule out an electrical open/short

1. 1

   Preparation

   Park the machine on a hard, level surface. Engage the parking brake, chock the front wheels, and safely lift and support the rear left side of the machine using heavy-duty jack stands rated for agricultural equipment.

2. 2

   Wheel Removal

   Remove the rear left wheel and tire assembly to gain access to the final drive/hub area.

3. 3

   Sensor Removal

   Locate the rear left wheel speed sensor. Remove the retaining bolt and carefully pull the sensor out of its mounting bore. Clean the bore thoroughly.

4. 4

   Hub/Axle Disassembly

   To replace the sensor ring, you typically must remove the wheel hub or pull the axle shaft, as the ring is press-fit onto the rotating assembly. Follow the specific Case IH service manual for your axle type to disassemble the hub.

5. 5

   Ring Replacement

   Remove the damaged sensor ring. Clean the mounting surface on the hub/axle to bare metal. Press or heat-shrink the new tone ring into place, ensuring it sits perfectly flush and square.

6. 6

   Reassembly

   Reinstall the hub/axle assembly.

7. 7

   Sensor Installation

   Install the wheel speed sensor. If the sensor tip was damaged by the broken ring, replace the sensor as well.

8. 8

   Final Steps

   Reinstall the wheel, torque the lug nuts to OEM spec, clear the fault codes using your diagnostic tool, and perform a test drive to verify the wheel speed signal is steady.