Case IH 12613 – ABS (Anti-lock Braking System) ECU / Module: Rear right wheel speed sensor - shorted to ground

The electrical circuit for the rear right wheel speed sensor has an unintended path to ground, pulling the signal voltage down and preventing the control module from reading the sensor's frequency.

• Case IH tractors (Steiger and Puma series)

1. 1

   Visually inspect the wiring harness routing from the rear right wheel speed sensor to the ABS module for chafing, melting, or pinched wires that could cause a short to the chassis.

2. 2

   Check the specific sensor lines (e.g., wire 9620 for the sensor and 9621 for the sensor return on Puma models) for continuity to ground.

3. 3

   Disconnect the sensor and check the pins on both the sensor side and the harness side for corrosion, moisture, or bent pins that could bridge the signal to ground.

4. 4

   With the sensor disconnected, test the harness side with a multimeter to see if the short to ground is in the wiring. If the harness tests good, the internal circuitry of the sensor itself is likely shorted.

1. 1

   Turn off the machine and disconnect the battery to ensure safety while working on the ABS electrical system.

2. 2

   Locate the rear right wheel speed sensor on the rear right axle/hub assembly.

3. 3

   Disconnect the sensor's electrical connector.

4. 4

   Using a digital multimeter, test the sensor's signal and return wires in the main harness for a short to ground.

5. 5

   If the harness is shorted: Trace the harness back to the ABS ECU, locate the damaged section of the wire (chafed insulation touching the frame), and repair the wire using OEM-approved splicing methods.

6. 6

   If the harness is good: The short is internal to the sensor. Remove the mounting bolt holding the rear right wheel speed sensor in place and remove the faulty sensor.

7. 7

   Install the new wheel speed sensor and torque the mounting bolt to OEM specifications.

8. 8

   Reconnect the sensor to the wiring harness.

9. 9

   Reconnect the battery, clear the fault codes from the ABS ECU, and test drive the tractor to ensure the ABS module is correctly reading the signal frequency and the code does not return.