Case IH 518683-01 - ACM – ACM (Armrest Control Module): Rear hitch settings selector knob internal failure

The system has detected an internal hardware or logic failure within the turn-and-press encoder dial (knob) used to adjust the rear hitch settings. The "-01" Failure Mode Indicator (FMI) typically designates an internal component fault or a signal that is valid but below the normal operational range.

• MAGNUM AFS Connect
• Steiger / Quadtrac AFS Connect
• Optum AFS Connect
• Puma AFS Connect

1. 1

   Inspect the rear hitch encoder dial on the Multicontroller armrest for physical damage, sticking, or liquid intrusion

2. 2

   Look for associated voltage codes on the same circuit (e.g., 518683-06 or 518683-13) which would indicate a wiring short or open circuit rather than an internal switch failure

3. 3

   Connect the Case IH Electronic Service Tool (EST) to the CAN1/ISOBUS diagnostic connector and monitor the ACM inputs live to see if the module registers any change in state when the knob is turned or pressed

4. 4

   Turn the key OFF and wait 2 to 5 minutes for the modules to power down completely before disconnecting the batteries. Reconnect and reboot to see if the internal failure was a temporary software glitch.

1. 1

   Power Down

   Turn the ignition OFF. Wait 2-5 minutes for the DEF system to purge and the ECUs to power down, then disconnect the battery.

2. 2

   Disassemble the Armrest

   Remove the retaining screws from the lower and upper housings of the Multicontroller armrest to access the internal ACM and switch assemblies.

3. 3

   Disconnect the Harness

   Locate the rear hitch settings selector encoder. Disconnect the CAN/wiring harness pigtail connecting the encoder to the ACM.

4. 4

   Remove the Faulty Knob

   Remove the mounting screws securing the encoder assembly to the armrest console bezel.

5. 5

   Install the New Part

   Seat the new encoder dial into the armrest console and secure it with the mounting screws.

6. 6

   Reconnect

   Plug the wiring harness back into the ACM. Ensure the connector is fully seated and locked.

7. 7

   Reassemble

   Reinstall the armrest housing panels and restore battery power.

8. 8

   Configuration/Calibration

   Connect the EST to the diagnostic port. Navigate to the ACM configuration menu (General Configuration) to clear the fault codes and verify that the new switch is communicating properly on the CAN VB1 bus.