Case IH 518683-13 - ACM – ACM: Rear hitch settings selector knob is disconnected

The control module has detected an open circuit, a loss of communication, or a missing signal from the potentiometer/knob used to adjust the rear hitch settings on the armrest console.

• MAGNUM AFS Connect
• Case IH Magnum Series (Magnum 235-340 Series 4 and newer AFS Connect models)
• Case IH Steiger Series

1. 1

   Check the physical connection at the rear hitch settings selector knob to ensure the plug has not vibrated loose or been accidentally disconnected.

2. 2

   Inspect the wiring harness between the ACM and the rear hitch settings selector knob for pinched, broken, or chafed wires.

3. 3

   Disconnect the knob and inspect the connector pins for corrosion, pushed-back pins, or moisture.

4. 4

   Verify that the potentiometer is receiving its 5-volt reference and ground from the ACM. Test the signal wire for continuity back to the ACM.

1. 1

   Power Down

   Turn off the tractor and disconnect the battery ground to prevent electrical spikes.

2. 2

   Access the Armrest Internals

   Carefully remove the necessary trim panels on the armrest console to access the underside of the rear hitch controls.

3. 3

   Reconnect/Repair Wiring

   If the connector is simply unplugged, securely reconnect it. If wiring damage is found during diagnostics, repair the broken wires or replace the damaged connector pigtail.

4. 4

   Replace the Knob/Potentiometer

   If the wiring and voltages test good but the code remains active, the internal potentiometer of the selector knob has failed. Remove the retaining hardware/clips holding the knob assembly in the armrest and install a new one.

5. 5

   Reassembly and Clearing Codes

   Reassemble the armrest, reconnect the battery, and turn the key on. Use an electronic service tool (EST) to clear the inactive 518683-13 fault code.

6. 6

   Calibration

   Test the rear hitch settings. A calibration of the armrest levers/knobs may be required upon power-up if a new component was introduced.