Case IH 520613-09 - ACM – Armrest Control Module (ACM): Rear hitch position control disconnected while powered on

Indicates an open circuit, loss of communication, or a missing voltage reference from the rear hitch position control potentiometer to the controller. The system detects that the voltage signal has dropped below the acceptable lower limit (or gone completely open) while the machine's key power is on.

• MAGNUM AFS Connect
• Case IH Magnum 235 - 340 (Series 4)
• Case Puma 165, 180, 195, 210, 225 CVX

1. 1

   Locate the rear hitch position control potentiometer and trace the wiring harness back to the ACM/ECU

2. 2

   Ensure the connectors are fully connected and not damaged. Verify that the pins are in the correct position, free of corrosion, and that the physical fit is tight

3. 3

   Disconnect the sensor and use a multimeter to check for continuity between the potentiometer connector and the ACM to rule out a broken wire or open circuit

1. 1

   Resolve Wiring Issues

   If the diagnostic checks reveal a broken wire or loose pin, repair or replace the affected section of the wiring harness.

2. 2

   Replace the Sensor

   If the wiring harness has continuity and the connectors are tight, the potentiometer itself has failed internally and must be replaced.

3. 3

   Clear Fault Codes

   Once the physical repair is made, clear the stored error codes. Depending on the tractor model, this can be done using the Electronic Service Tool or via the tractor's onboard diagnostic display (using the "HC" menu mode to erase stored codes without affecting calibration data).

4. 4

   Recalibrate

   Perform the hydraulic lift calibration procedure to ensure the ACM learns the sweep of the new position control potentiometer.