Case IH 518557-13 - ACM – ACM: Low voltage in EHR settings adjustment knob

The control module is receiving an out-of-range, low, or missing electrical signal from the encoder knob used to adjust the Electro-Hydraulic Remote (EHR) settings. This is typically caused by a short to ground, a failed internal potentiometer/encoder, or a disconnected/damaged wiring harness inside the armrest.

• MAGNUM AFS Connect
• Case IH Magnum AFS Connect Series (180, 200, 220, 240, 250, 280, 340, 380, 400)
• Case IH Steiger AFS Connect Series
• Case IH Puma AFS Connect Series

1. 1

   Physically inspect the EHR settings encoder knob on the MultiControl Armrest to see if it feels loose, binds, or lacks its normal detent 'click' when rotated.

2. 2

   Remove the armrest cover and inspect the wiring sub-harness connecting the EHR knob to the ACM for pinched wires, chafing against the frame, or loose connector pins.

3. 3

   Test the voltage at the encoder knob connector to check for a short to ground on the signal wire or a loss of the 5V reference supply.

4. 4

   Use the AFS Pro 1200 display diagnostics screen or the Case IH Electronic Service Tool (EST) to monitor the live voltage/position of the EHR knob. A 0V reading or lack of smooth change indicates internal encoder failure.

1. 1

   Power Down

   Turn off the tractor and disconnect the battery to prevent static discharge damage to the ACM.

2. 2

   Disassemble the Armrest

   Remove the retaining screws on the underside of the MultiControl Armrest to lift off the top console cover.

3. 3

   Isolate the Component

   Locate the EHR settings adjustment encoder knob assembly and disconnect its electrical pigtail from the ACM board.

4. 4

   Repair or Replace

   If the wiring harness is damaged, repair the broken/shorted wire. If the wiring is intact, the encoder knob itself has failed. Note: Depending on the specific armrest revision, Case IH often integrates these knobs directly into the ACM circuit board or a larger switch cluster, meaning the module or sub-assembly must be replaced.

5. 5

   Reassembly

   Install the new component, route the wiring carefully to avoid pinch points, and secure the armrest cover.

6. 6

   Calibration

   Reconnect the battery, power on the tractor, and clear the inactive fault codes. You may need to navigate to the AFS Pro 1200 "H-Menu" or use the EST to recalibrate the armrest controls so the ACM recognizes the new encoder's voltage sweep.