Case IH 518440-02 - ACM – ACM: Volume increase switch circuit fault

Indicates an electrical circuit failure—such as an open circuit, short to ground, or short to power—specifically on the circuit monitoring the radio/media volume increase button.

• MAGNUM AFS Connect
• Case IH Magnum AFS Connect series (Magnum 250, 280, 310, 340, 380, 400)
• Case IH Steiger / Quadtrac AFS Connect series
• Case IH Optum AFS Connect series

1. 1

   Connect the Case IH Electronic Service Tool (EST) to the CAN1/ISOBUS diagnostic connector, check the ACM for active vs. inactive codes, and monitor the live state of the volume switch

2. 2

   Inspect the volume increase switch/encoder knob on the Multicontroller armrest for physical damage, sticking, or liquid intrusion

3. 3

   Remove the armrest trim and inspect the wiring harness between the media switch pack and the ACM. Test the circuit for continuity, high resistance, or shorts to ground/power

4. 4

   Verify that the ACM is receiving proper voltage (Pin 1 - UNSW B+, Pin 2 - SWB+, and Pin 7 - GND)

1. 1

   Power Down

   Turn the ignition key to the OFF position. Wait 2 to 5 minutes before disconnecting the batteries to allow the DEF system to purge and the modules to power down correctly.

2. 2

   Disassembly

   Carefully remove the right-hand Multicontroller armrest covers to access the internal switch packs and the ACM.

3. 3

   Circuit Repair

   If the diagnostic checks revealed a damaged wire or loose connector pin between the switch and the ACM, repair the wiring harness.

4. 4

   Component Replacement

   If the wiring is intact but the switch fails continuity tests when pressed, replace the armrest media switch pack/encoder assembly. If the switch and wiring test perfectly but the fault remains active, the ACM itself has suffered an internal fault and must be replaced.

5. 5

   Reassembly & Calibration

   Reconnect the switch pack and ACM. Reinstall the armrest covers. Reconnect the battery.

6. 6

   Clear Codes

   Turn the key ON, connect the EST, clear the 518440-02 fault code, and test the volume increase function to ensure the radio responds and the code does not return.