Case IH 518423-06 - ACM – ACM: Hand throttle 2 voltage low

The control module is receiving a voltage signal from the secondary channel (Channel 2) of the hand throttle position sensor (potentiometer) that has dropped below the minimum acceptable threshold (typically below 0.2V - 0.5V). This condition is almost always caused by an open circuit, a short to ground in the sensor wiring, or an internal failure of the hand throttle potentiometer itself.

• MAGNUM AFS Connect
• Case IH Magnum Series
• Case IH Steiger Series
• Case IH Puma Series

1. 1

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

2. 2

   Disconnect the hand throttle sensor, turn the key to the ON position, and use a multimeter to verify the sensor is receiving a steady 5V reference supply and has a solid ground from the ACM.

3. 3

   Check the signal wire for continuity back to the ACM and ensure it is not shorted to ground.

4. 4

   Look for related 5V reference codes (e.g., ENG 443 or ENG 187). If multiple sensors report low voltage, the ACM's 5V power supply circuit may be compromised.

5. 5

   Attempt to recalibrate the hand throttle via the tractor's AFS Pro display monitor (Calibration Menu) to see if the sensor has simply fallen out of its calibrated range.

1. 1

   Power Down

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

2. 2

   Access the Sensor

   Remove the retaining screws on the right-hand armrest console to lift the upper plastic trim and access the throttle assembly.

3. 3

   Remove the Assembly

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

4. 4

   Install the New Part

   Mount the new hand throttle potentiometer or lever assembly into the console and secure the hardware.

5. 5

   Reassemble

   Reconnect the electrical harness and reinstall the armrest console trim.

6. 6

   Recalibrate

   Reconnect the battery and turn the key ON. You must perform the hand throttle calibration procedure using the tractor's display monitor so the ACM can learn the new minimum and maximum voltage values of the new sensor.

7. 7

   Clear Codes

   Clear the inactive fault codes and test the throttle operation.