Case IH 18004 – Armrest Controller (ARM): Hand throttle #2 -voltage too high

The signal voltage returning from the second potentiometer is exceeding the maximum expected threshold (typically above 4.5V to 4.8V). This is almost always caused by a short to power (5V or 12V) on the sensor's signal wire, an open/broken ground circuit leading to the potentiometer, or an internal short/failure of the hand throttle potentiometer itself.

• Magnum
• Steiger
• Puma
• Maxxum
• Optum

1. 1

   Monitor live data using the tractor's diagnostic display (e.g., Pro 700 / AFS Connect) to view the raw voltage for Hand Throttle #2. Observe if the voltage is pegged at 5V or fluctuates erratically when moving the lever.

2. 2

   Remove the armrest cover and visually inspect the wiring harness leading to the hand throttle. Look for broken or chafed wires just below the connector.

3. 3

   Unplug the hand throttle potentiometer and test the ground pin for continuity to the chassis, and check the reference voltage pin for a steady 5V.

4. 4

   Isolate the short: With the sensor unplugged and key ON, check the signal wire voltage. If voltage remains high, the harness is shorted to power. If voltage drops to zero, the potentiometer has failed internally.

1. 1

   Power Down

   Turn off the tractor, remove the key, and disconnect the battery to prevent electrical spikes.

2. 2

   Access the Assembly

   Remove the retaining screws on the armrest console to lift the cover and access the Multi-Function Handle (MFH) and hand throttle assembly.

3. 3

   Remove the Faulty Component

   Disconnect the electrical connector from the hand throttle. Remove the mounting hardware securing the throttle lever/potentiometer assembly to the armrest chassis.

4. 4

   Install the New Part

   Mount the replacement potentiometer or throttle assembly and reconnect the wiring harness.

5. 5

   Reassemble

   Carefully route the wiring to ensure it will not be pinched or stretched when the armrest is adjusted, then reinstall the console covers.

6. 6

   Recalibration

   You must perform a throttle calibration using the tractor's display monitor so the Armrest controller can learn the new minimum (idle) and maximum (full throttle) voltage sweeps of the new potentiometer.