Case IH 520193-03 - VCM – VCM / UCM: Redundant wheel angle sensor voltage high

The analog redundant wheel angle sensor is sending a voltage signal that exceeds the normal operational range (shorted to a power source higher than 4.9V). The controller flags this as a Severe error and forces the steering system into a safe state, disabling automated steering.

• MAGNUM AFS Connect
• Case IH Magnum AFS Connect series
• Case IH Puma series
• Case IH Steiger / Quadtrac series
• Case IH MX Magnum series

1. 1

   Verify in the display/diagnostic tool that the redundant wheel angle sensor is present and correctly mapped (Parameter P3245 should be set to 255 for 'Present')

2. 2

   Inspect the wiring harness connecting the redundant wheel angle sensor to the AD2 pin on the PVED-CLS controller for pinched wires, chafing, or melted insulation

3. 3

   Disconnect the sensor and inspect the pins for corrosion, moisture, or damage

4. 4

   Use a multimeter to check the signal voltage coming from the sensor; if it remains pegged above 4.9V regardless of steering angle, the sensor is internally shorted or wiring is shorted to power

1. 1

   Safety First

   Park the machine on a level surface, turn off the engine, and disconnect the battery power. Warning: Working around the steering axle and wheel angle sensor can be hazardous; always power off the vehicle when working near the steering axle.

2. 2

   Isolate the Fault

   Disconnect the redundant wheel angle sensor from the harness. Turn the key on and check the voltage on the signal wire of the harness. If high voltage is still present on the harness side, the wiring harness has a short to power and must be repaired or replaced.

3. 3

   Replace the Sensor

   If the harness tests fine, the sensor itself has an internal short. Remove the mounting hardware and linkage connecting the sensor to the steering axle/tie-rod.

4. 4

   Install New Sensor

   Mount the replacement sensor and reconnect the mechanical linkage and electrical connector.

5. 5

   Calibration

   Power up the machine and use the AFS Pro display or diagnostic tool to perform a Wheel Angle Sensor calibration so the controller can learn the new sensor's limits.