Case IH 519010-04 - UCM – UCM: Front suspension center position sensor voltage is low

The position sensor (a potentiometer) that monitors the travel and height of the suspended front axle is sending a voltage signal to the controller that has dropped below the expected absolute minimum limit (for example, reading below 740mV). This is typically caused by a sensor that has physically seized and broken off, a sensor that is out of physical adjustment, or a wiring circuit failure.

• MAGNUM AFS Connect
• Magnum Series (235-340, 275, 305)
• Puma Series (150, 165, 175, 180-260 CVT)
• Maxxum Series
• Vestrum Series

1. 1

   Visually inspect the potentiometer position sensor under the front left of the tractor at the front axle support to see if the suspension sensor shaft has seized or physically broken off.

2. 2

   Back-probe the wire side of the sensor connector with a multimeter to verify the voltage is within the expected operating range (above 740mV and below 5V). A reading stuck below the threshold indicates the sensor is out of adjustment or internally failed.

3. 3

   Inspect the sensor harness for an open circuit or a short to ground.

4. 4

   Verify that the rod-side and piston-side pressure transducers are reading correctly, as failures in these sensors will also prevent the suspension from calibrating.

1. 1

   Access the Sensor

   Locate the front suspension position sensor on the front axle assembly.

2. 2

   Remove the Old Sensor

   Disconnect the wiring harness and unbolt the potentiometer. If the shaft is seized or broken, ensure all debris is cleared from the mounting point.

3. 3

   Install the New Sensor

   Mount the replacement position sensor/angle rod.

4. 4

   Adjust the Sensor Position

   Before finalizing the installation, use your multimeter to monitor the sensor's voltage output. Adjust the physical position of the suspension pot so that the baseline voltage reads above the low-limit threshold (e.g., >740mV) but below 5V.

5. 5

   Run Calibration

   Once installed and adjusted, you must run the front suspension calibration cycle via the tractor's cab display. The tractor will automatically raise and lower the front axle to learn the new upper and lower travel limits.