Case IH 518595-00 - ACM – ACM (Armrest Control Module): Front hitch working position internal failure

The control module is receiving an erratic, out-of-range, or invalid signal from the front hitch position sensor (potentiometer). Because of this internal failure or signal mismatch, the system cannot accurately determine the physical height/position of the front hitch, which may disable automated hitch functions or cause it to default to a safe mode.

• MAGNUM AFS Connect
• Magnum Series (including AFS Connect Magnum 180–400)
• Puma Series (e.g., 165, 180, 195, 210, 225)
• Maxxum Series
• Steiger / Quadtrac Series

1. 1

   Inspect the physical linkage connecting the front hitch to the rotary position potentiometer. Ensure the linkage is not bent, disconnected, or packed with debris.

2. 2

   Trace the wiring harness from the front hitch position sensor back to the ACM. Look for rubbed wires, pinched harnesses, or corrosion inside the sensor connector.

3. 3

   Using a multimeter, verify that the sensor is receiving a steady 5V reference voltage and has a solid ground. Back-probe the signal wire while manually raising and lowering the hitch to see if the voltage scales smoothly; dead spots indicate a failed potentiometer.

4. 4

   Check if there is a pending software update for the ACM. Case IH has previously released ACM software updates to resolve erratic remote and hitch behavior.

1. 1

   Prepare the Machine

   Park the tractor on a flat, level surface. Lower the front hitch completely to the ground to relieve all hydraulic pressure. Turn off the engine and remove the key.

2. 2

   Locate the Sensor

   Locate the front hitch position potentiometer, typically mounted on the side of the front hitch frame where it connects to the lift arm pivot.

3. 3

   Remove the Old Sensor

   Disconnect the 3-pin electrical connector from the sensor. Remove the retaining bolts/screws (usually M5 or M6 bolts) securing the sensor bracket and linkage.

4. 4

   Install the New Sensor

   Mount the new potentiometer and reattach the physical linkage arm. Ensure the sensor is oriented correctly so that the hitch's full range of motion stays within the sensor's sweep. Tighten the mounting hardware.

5. 5

   Reconnect

   Plug the electrical connector back into the sensor.

6. 6

   Calibration

   Turn the tractor's ignition on. You must perform a front hitch calibration using the in-cab display or the Case IH Electronic Service Tool (EST). This allows the ACM to learn the new sensor's minimum (lowered) and maximum (raised) voltage limits.