Case IH 18025 – Armrest Controller: Rear hitch slip control potentiometer - voltage too low.

The system has detected that the signal voltage returning from the rear hitch slip control potentiometer to the controller has dropped below the minimum acceptable threshold (below 0.2 V).

• Magnum
• Steiger T4B
• Magnum 235
• Magnum 260
• Magnum 290
• Magnum 340 (Series 4)
• Puma 165
• Puma 180
• Puma 195
• Puma 210
• Puma 225 CVX
• Steiger 350 to 600 (4WD models)
• Maxxum 115U
• Maxxum 135
• Maxxum 145
• Maxxum 150
• Farmall Pro 115U
• Farmall Pro 135
• Farmall Pro 145
• Farmall Pro 150

1. 1

   Inspect the slip control potentiometer knob on the right-hand armrest for physical damage, sticking, or liquid intrusion.

2. 2

   Access the wiring harness beneath the armrest console, disconnect the plug at the slip control potentiometer, and check for loose pins, corrosion, or backed-out terminals.

3. 3

   Turn the key to the ON position and verify that the potentiometer is receiving a 5V reference signal and has a solid ground connection from the Armrest Control Module.

4. 4

   Back-probe the signal wire and slowly turn the slip control knob from minimum to maximum. The voltage should smoothly sweep between 0.5V and 4.5V. If stuck below 0.2V, the potentiometer is internally faulty.

5. 5

   Disconnect the harness from the Armrest Control Module and check the signal wire for continuity. Ensure the signal wire is not shorted to the chassis ground.

1. 1

   Power Down

   Turn off the tractor, remove the key, and disconnect the negative battery cable to prevent electrical shorts while working on the armrest modules.

2. 2

   Disassemble the Armrest

   Remove the retaining screws securing the top cover or side access panels of the right-hand Multicontroller armrest console.

3. 3

   Locate the Component

   Locate the rear hitch slip control potentiometer (usually grouped with the draft, position, and drop-rate control knobs).

4. 4

   Remove the Knob

   Carefully pull or pry the plastic control knob off the top of the potentiometer shaft (some knobs may have a small set screw).

5. 5

   Extract the Potentiometer

   Disconnect the electrical pigtail/connector from the potentiometer. Unscrew the retaining nut holding the threaded shaft of the potentiometer to the armrest panel and pull the unit out from underneath. (Note: On some specific Puma/Magnum configurations, the potentiometers are soldered directly to a printed circuit board [e.g., EDC Panel Board]. If this is the case, the entire sub-board must be replaced).

6. 6

   Install the New Part

   Insert the new potentiometer through the panel, secure it with the retaining nut, and press the control knob back onto the shaft.

7. 7

   Reassembly

   Reconnect the electrical connector and reassemble the armrest console covers.

8. 8

   Test and Calibrate

   Reconnect the battery. Turn the key ON and clear the inactive fault codes via the tractor's display monitor. Test the slip control knob to ensure the 18025 code does not return. A routine armrest controller calibration may be required via the display terminal so the ACM can learn the new potentiometer's exact minimum and maximum voltage values.