Case IH 518588-03 - UCM – UCM: Brake assisted steering right wheel speed sensor voltage high

The control module is receiving a voltage signal from the right wheel speed sensor that exceeds the maximum expected threshold. This condition is typically caused by a short to power (such as a 5V or 12V supply line shorting to the signal wire), a loss of the sensor's ground circuit, or an internal failure within the sensor itself.

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

1. 1

   Inspect the brake-assisted steering wire harness routing down to the right wheel hub/axle for chafed insulation, pinched wires, or exposed copper that could cause a short to power.

2. 2

   Disconnect the right wheel speed sensor and inspect the electrical connector for water ingress, corrosion, or bent pins.

3. 3

   With the key ON and engine OFF, use a digital multimeter to probe the sensor's harness connector. Verify the 5V reference voltage, ground continuity, and ensure the signal wire is not carrying stray voltage.

4. 4

   Temporarily swap the right wheel speed sensor with the left wheel speed sensor. If the fault code shifts to the left side, the sensor is internally shorted. If it remains on the right, the issue is in the UCM or wiring harness.

1. 1

   Park the tractor on a level surface, apply the parking brake, turn off the engine, and disconnect the battery ground cable to protect the UCM.

   Park the tractor on a level surface, apply the parking brake, turn off the engine, and disconnect the battery ground cable to protect the UCM.

2. 2

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

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

3. 3

   Depress the locking tab and disconnect the electrical wiring harness from the sensor.

   Depress the locking tab and disconnect the electrical wiring harness from the sensor.

4. 4

   Remove the retaining bolt(s) securing the sensor to the mounting bracket or axle housing.

   Remove the retaining bolt(s) securing the sensor to the mounting bracket or axle housing.

5. 5

   Carefully pull the sensor straight out of its bore.

   Carefully pull the sensor straight out of its bore.

6. 6

   Clean the mounting surface and the bore to ensure no dirt or debris falls into the assembly and that the new sensor will seat flush.

   Clean the mounting surface and the bore to ensure no dirt or debris falls into the assembly and that the new sensor will seat flush.

7. 7

   Insert the new wheel speed sensor and tighten the retaining bolt to the OEM torque specification.

   Insert the new wheel speed sensor and tighten the retaining bolt to the OEM torque specification.

8. 8

   Reconnect the electrical harness, ensuring the weather seal is intact and the connector clicks into place.

   Reconnect the electrical harness, ensuring the weather seal is intact and the connector clicks into place.

9. 9

   Reconnect the battery.

   Reconnect the battery.

10. 10

    Turn the key ON and use the AFS Pro 1200 display or a diagnostic service tool to clear the UCM fault codes.

    Turn the key ON and use the AFS Pro 1200 display or a diagnostic service tool to clear the UCM fault codes.

11. 11

    Test drive the tractor, performing headland turns to engage the brake-assisted steering system, and verify that the fault code does not return.

    Test drive the tractor, performing headland turns to engage the brake-assisted steering system, and verify that the fault code does not return.