Case IH 518668-02 - ACM – ACM: Mouse memory switch circuit fault

An electrical anomaly—such as an open circuit, short circuit, or out-of-range voltage—specifically on the memory switch circuit of the encoder dial (mouse) located on the MultiControl Armrest.

• MAGNUM AFS Connect
• Case IH Magnum AFS Connect Series
• Case IH Steiger / Quadtrac AFS Connect Series
• Case IH Optum AFS Connect Series

1. 1

   Check for companion codes: Look for related ACM codes (such as 518667-02, 518666-19, or 518666-06) that might indicate a broader harness failure or complete disconnection.

2. 2

   Perform a functionality test: Turn on the AFS Pro 1200 display and test if the encoder dial can still navigate the menus, radio, or HVAC. If the dial works but the memory hotkeys do not, the issue is isolated to the switch itself.

3. 3

   Inspect the wiring harness: Check the harness connecting the encoder dial to the Armrest Control Module (ACM). Look for pinched wires inside the armrest housing, loose connector pins, or corrosion.

4. 4

   Perform a voltage/continuity test: Test the memory switch circuit for continuity. If the wiring harness tests good from the ACM connector to the mouse connector, the fault is internal to the encoder dial assembly.

1. 1

   Power Down

   Turn off the tractor and disconnect the battery to prevent electrical shorts while working inside the armrest console.

2. 2

   Disassemble the Armrest

   Carefully remove the upper trim panels of the MultiControl Armrest to expose the underside of the control layout and the ACM.

3. 3

   Disconnect the Mouse

   Locate the encoder dial (mouse) assembly and unplug its electrical connector.

4. 4

   Remove the Faulty Component

   Remove the retaining screws holding the encoder dial assembly to the armrest tray.

5. 5

   Install the New Part

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

6. 6

   Reconnect

   Plug the electrical harness back into the new encoder dial. Ensure the connection to the ACM is also fully seated.

7. 7

   Reassemble and Clear Codes

   Reinstall the armrest trim panels. Reconnect the battery, power on the tractor, and use the AFS Pro 1200 display (or a dealer diagnostic tool) to clear the inactive 518668-02 fault code. Test the memory switch for proper operation.