Case IH 99 – Armrest Controller (ARM / TMF): Aux 2nd remote valve FLOW potentiometer is failed.

The controller is receiving an out-of-range, erratic, or missing voltage signal from the rotary potentiometer dial that the operator uses to set the hydraulic flow rate for the #2 auxiliary remote valve. This is usually caused by a worn carbon track inside the potentiometer, a broken wire, or a failed component on the armrest circuit board.

• MX Magnum
• STX Steiger
• Steiger / STX Series 4WD Tractors
• STX 280
• STX 435
• STX 500
• 335
• 450
• 550QT
• Magnum / MX Magnum Series
• MX180
• MX215
• Magnum 305
• 310
• TG Series
• Puma Series

1. 1

   Cycle the tractor power to see if the fault is intermittent; a simple reboot will sometimes temporarily restore hydraulic remote response.

2. 2

   Perform a sweep test by slowly turning the 2nd remote flow dial while monitoring the diagnostic screen to check for a 'bad spot' or dropping signal.

3. 3

   Access the armrest controller board to check the wiring harness and connector going to the 2nd remote flow potentiometer for loose pins or broken wires.

4. 4

   Verify that the Armrest Controller is supplying the correct reference voltage (typically 5V) and ground to the potentiometer.

5. 5

   Using a multimeter, test the potentiometer's resistance for a smooth sweep (commonly 1000 ohms or 3000 ohms total resistance) without any open circuits.

1. 1

   Disconnect Power

   Turn off the tractor and disconnect the battery to prevent shorting the sensitive armrest circuit boards.

2. 2

   Disassemble the Armrest

   Remove the retaining screws securing the armrest console cover/panel to access the internal circuit boards and the back of the control dials.

3. 3

   Locate the Component

   Identify the potentiometer specifically linked to the 2nd auxiliary remote flow control dial.

4. 4

   Disconnect

   Unplug the electrical connector from the back of the potentiometer.

5. 5

   Remove the Potentiometer

   Remove the control knob from the top of the armrest. Then, remove the retaining nut (typically a 3/8-32 nut) securing the potentiometer to the armrest panel and pull the unit out.

6. 6

   Install the New Part

   Insert the replacement potentiometer, secure it with the retaining nut, and reattach the control knob.

7. 7

   Reassemble and Calibrate

   Reconnect the electrical harness, reassemble the armrest console, and reconnect the battery. Clear the fault codes. Depending on the tractor model, you may need to run an armrest calibration procedure via the display monitor so the controller can learn the new potentiometer's minimum and maximum voltage values.