Case IH 518434-01 - ACM – ACM: Internal failure in the auxiliary wheel (thumbwheel) of the multifunction handle

The internal circuitry or sensor of the auxiliary wheel (thumbwheel) used to control specific tractor functions has failed.

• MAGNUM AFS Connect
• Magnum Series
• Magnum 250-380
• Magnum 290 CVT
• AFS Connect Magnum
• Steiger Series
• Puma Series
• Maxxum Series

1. 1

   Connect the Electronic Service Tool (EST) to the vehicle and scan for all active Diagnostic Trouble Codes (DTCs).

2. 2

   Check for related codes (e.g., 518434-06 for low voltage, 518434-03 for high voltage, or 518434-09 for disconnected) which could indicate a wiring harness issue rather than a failed thumbwheel.

3. 3

   Remove the armrest casing and disassemble it to visually inspect the wiring. Check all connections for security on the armrest controller (ACM) to ensure the handle hasn't simply come unplugged or suffered wire chafing.

1. 1

   Disconnect power

   Power down the tractor and disconnect the battery to prevent electrical shorts.

2. 2

   Access handle base

   Disassemble the armrest console to access the base of the Multi-Function Handle.

3. 3

   Disconnect wiring

   Disconnect the handle's wiring harness from the Armrest Control Module (ACM).

4. 4

   Remove mounting hardware

   Remove the mounting hardware securing the joystick/handle to the armrest (typically M6 x 25mm or M6 x 16mm screws).

5. 5

   Remove handle

   Remove the faulty Multi-Function Handle.

6. 6

   Install new handle

   Install the new Multi-Function Handle and secure it with the mounting screws.

7. 7

   Reconnect wiring

   Reconnect the wiring harness to the ACM.

8. 8

   Reassemble console

   Reassemble the armrest console casing.

9. 9

   Restore power

   Reconnect the battery and power on the tractor.

10. 10

    Calibrate and clear codes

    Perform an SCV/Armrest calibration using the tractor's Pro display or the EST software to ensure the ACM recognizes the new handle's inputs. Clear the fault codes.