Case IH 518422-06 - ACM – ACM: Hand throttle 1 voltage low

The signal voltage from the Hand Throttle 1 position sensor (potentiometer) has dropped below the minimum acceptable threshold, indicating an open circuit, a short to ground, or a complete internal failure of the potentiometer.

• MAGNUM AFS Connect
• Case IH Magnum series
• Case IH Steiger / Quadtrac series
• Case IH Puma series
• Case IH Optum series

1. 1

   Visual Inspection: Inspect the wiring harness and connectors between the hand throttle potentiometer and the ACM inside the armrest console. Look for pinched wires, corrosion, or loose pins.

2. 2

   Voltage Supply Check: Using a multimeter, verify that the potentiometer is receiving its 5V reference supply and has a solid ground from the ACM. If the 5V reference is missing, check for other active fault codes.

3. 3

   Signal Sweep Test: Back-probe the signal wire with a multimeter. Slowly move the hand throttle from the idle position to maximum throttle. The voltage should transition smoothly without any dropouts or dead spots.

4. 4

   Continuity Test: Check for a short to ground or an open circuit in the signal wire between the throttle connector and the ACM harness.

1. 1

   Power Down

   Turn off the tractor and disconnect the battery power to prevent electrical spikes.

2. 2

   Access the Sensor

   Remove the retaining screws and lift the upper cover of the right-hand armrest console to access the internal Multicontroller assembly and hand throttle linkage.

3. 3

   Disconnect

   Unplug the electrical connector leading to the hand throttle potentiometer.

4. 4

   Replace

   If the sensor failed the sweep test, remove the mounting hardware securing the hand throttle potentiometer (or the integrated hand throttle assembly, depending on the specific cab trim) and install the replacement part.

5. 5

   Reassemble

   Reconnect the wiring harness, ensuring the connector clicks into place securely. Reinstall the armrest console cover.

6. 6

   Restore Power

   Reconnect the battery power and turn the key to the ON position.

7. 7

   Calibration

   Perform a hand throttle calibration procedure via the tractor's display monitor (e.g., Pro 700 or Pro 1200 display). Navigate to the calibration menu, select the hand throttle, and follow the on-screen prompts to move the throttle to its minimum and maximum limits.