Case IH U01 – Suspension Controller / Electronic Control Module: Front axle potentiometer open circuit - ACP will not work.

The control module is not receiving a valid voltage signal from the front axle suspension position sensor (potentiometer) and has detected an open circuit. Because the system cannot determine the height or position of the front axle, the Auto Calibration Procedure (ACP) for the front suspension is disabled and will not function.

• Puma/Mid Range Magnum
• MXM
• Case IH MXM Series
• Case IH Puma Series
• Case IH Magnum Series
• Case IH Maxxum Series
• Case IH Optum Series
• Case IH Steiger

1. 1

   Inspect the wiring harness leading to the front axle potentiometer for physical damage, disconnected plugs, or broken wires.

2. 2

   Check the signal ground wire on the potentiometer circuit to verify if it is open.

3. 3

   Enter the tractor's electronic calibration mode (H-Menu or ACP mode) and check the live displayed potentiometer reading. If the live reading is less than 51, 10, or 240 (depending on model), the sensor is confirmed dead/open.

1. 1

   Secure the Machine

   Park the tractor on a level surface, engage the parking brake, and ensure the front suspension is safely supported if you need to work near the axle linkage.

2. 2

   Trace the Circuit

   Locate the front axle potentiometer on the front suspension linkage. Disconnect the sensor pigtail and use a multimeter to verify that the sensor is receiving reference power and has a solid ground.

3. 3

   Repair Wiring (If Applicable)

   If the ground or signal wire is broken, repair the harness. If the wiring is intact and power/ground are present, the sensor itself has failed internally (open circuit).

4. 4

   Replace the Sensor

   Unbolt the faulty potentiometer from the front axle linkage. Install the new OEM potentiometer and reconnect the wiring harness.

5. 5

   Run the ACP

   Start the tractor and initiate the Auto Calibration Procedure (ACP) for the front suspension. The system must learn the minimum and maximum travel limits of the new sensor to clear the U01 code and restore suspension functionality.