Case IH 520556-02 - ACM – ACM: Engine monitor shortcut switch circuit fault

A circuit fault (typically an open circuit, short to ground, or short to power) originating from the physical switch located on the tractor's armrest console.

• MAGNUM AFS Connect
• Magnum 180 AFS Connect
• Magnum 200 AFS Connect
• Magnum 220 AFS Connect
• Magnum 240 AFS Connect
• Magnum 250 AFS Connect
• Magnum 280 AFS Connect
• Magnum 310 AFS Connect
• Magnum 340 AFS Connect
• Magnum 380 AFS Connect
• Magnum 400 AFS Connect

1. 1

   Verify the Active Code: Use the Electronic Service Tool (EST) to confirm whether the active code is 520556-02 (Engine monitor shortcut) or 520557-02 (A/C temp decrease).

2. 2

   Check ACM Connections: Inspect all connectors leading to the Armrest Control Module (ACM). Ensure the connectors are fully seated, not damaged, and that the pins are in the correct position without corrosion.

3. 3

   Clear and Retest: Make a note of the error code, clear it using the diagnostic tool, and test the switch for normal operation to see if the fault is active or stored/intermittent.

4. 4

   Software Verification: Check the ACM software version to ensure it is up to date (e.g., software part number 48010791 or 51511061 depending on the specific Magnum model).

1. 1

   Power down and disconnect battery

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

2. 2

   Disassemble armrest console

   Disassemble the armrest console to access the Armrest Control Module (ACM) and the switch panel.

3. 3

   Inspect wiring harness

   Inspect the wiring harness between the specific switch (A/C decrease or Engine monitor shortcut) and the ACM for chafing, pinches, or breaks.

4. 4

   Test switch continuity

   Test the switch for continuity. If the switch fails the continuity test, replace the switch or the integrated armrest switch panel.

5. 5

   Replace ACM if necessary

   If the switch and wiring are intact but the code persists, the ACM itself may be faulty and require replacement.

6. 6

   Reassemble and verify

   Reassemble the armrest, reconnect the battery, and use the EST to clear the fault code and verify the repair.