Case IH 518422-00 - ACM – ACM (Armrest Control Module): Hand throttle 1 internal failure

The system has detected an internal electrical failure or signal mismatch within the primary hand throttle potentiometer/encoder. The hand throttle translates the operator's lever movement into a voltage signal. When the module detects that the signal is missing, erratic, or out of its calibrated physical bounds without a direct short-to-ground or short-to-power (which have their own specific codes like -03 or -06), it logs an internal failure.

• MAGNUM AFS Connect
• Case IH Magnum AFS Connect Series (Models 250, 280, 310, 340, 380, 400)
• Case IH Steiger & Quadtrac AFS Connect Series

1. 1

   Check the hand throttle lever on the Multicontroller armrest for physical damage, binding, or excessive play that might push the potentiometer past its mechanical limits.

2. 2

   Remove the armrest trim and inspect the wiring harness connecting the hand throttle to the ACM. Look for loose pins, backed-out wires, or chafing.

3. 3

   Verify that the hand throttle potentiometer is receiving a steady 5V reference and a solid ground from the ACM.

4. 4

   Connect the Case IH Electronic Service Tool (EST). Monitor the Throttle #1 position parameter. Slowly sweep the hand throttle from idle to full throttle. The voltage/percentage should increase smoothly. If the signal drops out, spikes, or freezes, the potentiometer is internally faulty.

5. 5

   Look for related codes such as 518422-03 (Voltage High), 518422-06 (Voltage Low), or 518422-13 (Sensor Mismatch). If only 518422-00 is present, it heavily points to a failed sensor rather than a severed wire.

1. 1

   Prep the Machine

   Park the tractor on a level surface, turn off the engine, apply the parking brake, and disconnect the negative battery cable to prevent electrical shorts.

2. 2

   Access the ACM

   Carefully pry up and remove the plastic trim covers on the Multicontroller armrest console to expose the internal switches and potentiometers.

3. 3

   Remove the Hand Throttle

   Locate the hand throttle assembly. Disconnect the electrical pigtail connector from the throttle potentiometer.

4. 4

   Dismount the Sensor

   Remove the mounting screws (typically M4 hex/torx screws) holding the potentiometer and grip assembly to the armrest chassis.

5. 5

   Install the New Part

   Mount the replacement potentiometer, ensuring the physical tangs align correctly with the lever mechanism. Secure it with the mounting screws.

6. 6

   Reassemble

   Reconnect the electrical connector (ensure it clicks), and snap the armrest trim panels back into place.

7. 7

   Calibrate

   Reconnect the battery. Connect the Case IH EST laptop. Navigate to the ACM configuration and perform a Hand Throttle Calibration to teach the ACM the new minimum (0%) and maximum (100%) voltage limits of the new sensor. Clear the fault codes.