Case IH 518413-06 - ACM – Armrest Control Module (ACM): Display Navigation Encoder Knob Circuit - Voltage Below Normal or Shorted to Ground

The control module has detected a low voltage condition or a short-to-ground in the circuit of the display navigation knob.

• MAGNUM AFS Connect
• Magnum
• Steiger
• Quadtrac
• Optum
• Puma
• Axial-Flow 250
• Axial-Flow 260
• Axial-Flow AF
• Patriot 50

1. 1

   Verify system voltage (battery and alternator output) is within the normal 12–14V range, as low system voltage can trigger false ACM codes.

2. 2

   Inspect the navigation knob on the armrest for physical damage, sticking, or signs of liquid intrusion (e.g., spilled drinks or cab cleaning chemicals).

3. 3

   Open the armrest console and inspect the wiring harness between the encoder knob and the ACM board for chafed wires, pinched harnesses, or bent pins at the connector.

4. 4

   Disconnect the encoder knob and use a multimeter to check the supply voltage from the ACM to the knob. Check the signal wire for continuity to ground. If the signal wire is grounded while disconnected, the harness is shorted. If the harness tests fine, the encoder knob is internally shorted.

1. 1

   Power Down

   Turn off the machine and disconnect the battery to prevent electrical damage to the ACM during disassembly.

2. 2

   Access the Armrest Internals

   Remove the retaining screws securing the top cover/trim of the Multicontroller armrest. Carefully lift the panel to expose the internal control boards and switches.

3. 3

   Disconnect the Component

   Locate the display navigation encoder knob assembly and carefully unplug its electrical connector from the ACM harness.

4. 4

   Remove the Faulty Knob

   Remove the mounting hardware or retaining clips securing the encoder knob to the armrest bezel.

5. 5

   Install the New Part

   Seat the replacement encoder knob into the armrest panel and secure it with the retaining hardware.

6. 6

   Reassemble

   Reconnect the electrical connector, ensuring it clicks fully into place. Carefully reinstall the armrest cover, ensuring no wires are pinched in the housing.

7. 7

   Clear Codes & Test

   Reconnect the battery and turn the ignition on. Use the AFS display or the Electronic Service Tool (EST) to clear the inactive 518413-06 fault code. Rotate and press the new navigation knob to verify it correctly navigates the AFS display menus.