Case IH 18003 – Armrest Controller (ARM / Armrest ECU): Hand throttle #2 - voltage too low

This code indicates that the signal voltage returning from the secondary hand throttle potentiometer has dropped below the acceptable minimum threshold. This condition is typically caused by an open circuit (broken wire), a short to ground in the signal wire, or an internal failure of the potentiometer itself.

• Magnum
• Steiger
• Puma

1. 1

   Remove the armrest cover and inspect the wiring harness leading to the hand throttle potentiometer. Look for pinched wires, chafing, or disconnected plugs.

2. 2

   Disconnect the hand throttle connector and inspect the pins for corrosion, moisture, or pushed-out pins.

3. 3

   Turn the key ON (engine off). Using a multimeter, verify that the potentiometer is receiving a steady 5V reference and has a good ground from the Armrest Controller.

4. 4

   Use the Case IH Electronic Service Tool (EST) or the tractor's integrated diagnostic display to monitor the live voltage of 'Hand throttle #2 position'. Slowly move the throttle lever; the voltage should sweep smoothly. If it reads 0V or drops out erratically, the potentiometer or its wiring is faulty.

1. 1

   Power Down

   Turn off the tractor and disconnect the negative battery cable to prevent electrical shorts.

2. 2

   Access the Assembly

   Carefully remove the right-hand armrest console covers/trim to expose the internal throttle lever mechanics and wiring.

3. 3

   Remove the Faulty Component

   Disconnect the electrical connector from the hand throttle potentiometer. Remove the retaining screws/hardware holding the potentiometer or the throttle lever assembly in place.

4. 4

   Install the New Part

   Mount the replacement potentiometer (or complete grip/lever assembly) and secure the hardware.

5. 5

   Reconnect

   Plug the electrical connector back in, ensuring it clicks securely. Reassemble the armrest console covers.

6. 6

   Restore Power

   Reconnect the negative battery cable.

7. 7

   Calibration (Crucial Step)

   You must perform a hand throttle calibration using the tractor's display monitor or the EST software. This allows the Armrest Controller to learn the new minimum and maximum voltage values of the replacement potentiometer.

8. 8

   Clear Codes

   Clear the 18003 fault code from the Armrest Controller and test the tractor to ensure the throttle responds correctly without throwing the code again.