Case IH 12615 – MIU (Machine Information Unit) or ABS / TECU (Traction/Transmission Electronic Control Unit): Front right wheel speed sensor - shorted to ground

A hard electrical fault where the signal or power circuit for the front right wheel speed sensor has a direct, unintended path to the chassis ground (0 volts). Because the voltage is being pulled to ground, the control module cannot read the frequency/pulses generated by the sensor, resulting in a loss of wheel speed data.

• Magnum
• Maxxum
• Puma
• Optum
• Steiger
• SR
• SV
• TR
• TV

1. 1

   Visual Harness Inspection: Inspect the wiring harness leading to the front right wheel hub for rubbed-through insulation, pinched wires, or damage from field debris.

2. 2

   Connector Check: Disconnect the front right wheel speed sensor pigtail and inspect the pins for corrosion, water intrusion, or bent terminals.

3. 3

   Multimeter Ground Test: With the sensor disconnected and the key OFF, use a digital multimeter to check for continuity between the sensor's signal wire (on the machine harness side) and a known good chassis ground.

4. 4

   Sensor Internal Short Test: Test the sensor side of the connector to see if the sensor itself shows a dead short to ground across its internal circuitry.

1. 1

   Disconnect battery

   If the harness is damaged: Disconnect the machine's battery.

2. 2

   Locate damage

   Locate the chafed or pinched section of the wiring harness.

3. 3

   Splice wire

   Cut out the damaged wire and splice in a new section using waterproof, heat-shrink butt connectors to prevent future moisture intrusion.

4. 4

   Protect harness

   Wrap the repaired section in protective split-loom tubing and secure it with zip ties, ensuring there is enough slack for full steering lock and axle oscillation.

5. 5

   Disconnect battery

   If the sensor is faulty: Disconnect the battery.

6. 6

   Disconnect pigtail

   Disconnect the electrical pigtail from the front right wheel speed sensor.

7. 7

   Remove retaining bolt

   Remove the retaining bolt holding the sensor into the front right axle housing/hub.

8. 8

   Remove sensor

   Carefully pull the sensor straight out. (If it is seized, use penetrating oil and gently twist; do not snap it off inside the housing).

9. 9

   Clean bore

   Clean the mounting bore with a rag and ensure no debris falls into the tone ring area.

10. 10

    Lubricate O-ring

    Apply a light coat of clean grease or oil to the O-ring of the new sensor.

11. 11

    Install sensor

    Push the new sensor into the bore and torque the retaining bolt to OEM specifications.

12. 12

    Reconnect pigtail

    Reconnect the electrical pigtail.

13. 13

    Clear codes

    Reconnect the battery, turn the key ON, and clear the fault codes via the diagnostic display. A short test drive may be required for the MIU to register the new speed signal and turn off the warning light.