Case IH 1003 - UCM – UCM: Speed sensor error

The system detects that the radar speed is much greater than the wheel speed or there is a general failure in the speed sensor signal.

• VESTRUM CVX
• Case IH Puma
• Case IH Magnum
• Case IH Steiger
• Case IH Maxxum

1. 1

   Visually inspect the speed sensor, pins, and connector status for any signs of corrosion or physical damage.

2. 2

   Perform a resistance test across the sensor pins with the sensor disconnected and at ambient temperature. A healthy inductive speed sensor should read approximately 450 Ohms +/- 20 Ohms when stopped.

3. 3

   Check for an alternating voltage signal from the sensor while the gear/wheel is turning.

4. 4

   Check the wiring harness between the sensor and the UCM for continuity, and ensure there is proper insulation (no shorts to power, ground, or across wires).

5. 5

   If equipped with a radar ground speed sensor, connect a scope or multimeter to the radar electrical connector (often located on the left-hand side of the engine) and drive the vehicle to verify it is outputting a correct signal.

1. 1

   Locate the Sensor

   Identify the location of the wheel speed sensor (usually on the transmission/axle housing) or the radar ground speed sensor.

2. 2

   Disconnect and Inspect

   Unplug the sensor harness. Clean any dirt or corrosion from the connector pins.

3. 3

   Test the Sensor

   Perform the 450-ohm resistance test and the rotational voltage test outlined in the diagnostic steps.

4. 4

   Test the Harness

   If the sensor passes, use a multimeter to verify continuity from the sensor connector back to the UCM. Repair any broken or chafed wires.

5. 5

   Replace the Sensor

   If the sensor fails the resistance or voltage test, remove the mounting bolt, extract the faulty sensor, and install a new OEM speed sensor.

6. 6

   Clear Codes and Test

   Reconnect the harness, clear the fault codes from the UCM using the cab display or a diagnostic tool, and test drive the tractor to ensure the wheel speed and radar speed match without triggering the code.