Case IH 518588-04 - UCM – UCM: Brake assisted steering right wheel speed sensor voltage low

The control module is detecting a lower-than-expected voltage signal (or a short to ground) on the circuit for the right wheel speed sensor. This sensor is a critical input for the automated brake-assisted steering system, which applies the inside brake during headland turns to reduce the turning radius.

• MAGNUM AFS Connect
• Magnum AFS Connect 250
• Magnum AFS Connect 280
• Magnum AFS Connect 310
• Magnum AFS Connect 340
• Magnum AFS Connect 380
• Magnum AFS Connect 400
• Magnum Rowtrac

1. 1

   Verify overall battery and alternator voltage (low system voltage dropping below 11.5V can cause sensor voltage faults)

2. 2

   Inspect the brake-assisted steering wiring harnesses (groups 55.047.100 or 55.047.110) for chafing, pinch points, or damage near the rear axle/track assembly

3. 3

   Disconnect the right wheel speed sensor and check the connector for water intrusion, corrosion, or pushed-back pins

4. 4

   Verify the 5V reference supply and ground from the UCM to the sensor

5. 5

   Check the signal wire for continuity back to the UCM and test for a short to ground

1. 1

   Power Down

   Turn off the tractor and turn the battery disconnect switch to the OFF position.

2. 2

   Access the Sensor

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

3. 3

   Wiring Repair (If Applicable)

   If the diagnostic tests revealed a short to ground or a broken wire in the brake-assisted steering harness, splice and repair the wire using OEM-approved weather-sealed connectors.

4. 4

   Sensor Replacement

   If the wiring tests good but the sensor fails to output the correct voltage, the sensor has failed internally. Remove the retaining bolt, pull the old sensor from the housing, and install the new sensor.

5. 5

   Reassembly & Calibration

   Reconnect the sensor harness. Restore battery power.

6. 6

   Validation

   Clear the UCM fault codes using the AFS Pro 1200 display or the electronic service tool. Test drive the tractor and perform a sharp right-hand turn to verify that the brake-assisted steering engages the right brake without logging the 518588-04 code.