Case IH 518423-03 - ACM – ACM: Hand throttle #2 - voltage too high

The control module is receiving a voltage signal from the secondary hand throttle position potentiometer that is above the maximum expected range. This is typically caused by a failed potentiometer, a short to a high-voltage source in the wiring harness, or a loss of the sensor ground.

• MAGNUM AFS Connect
• Magnum 235
• Magnum 245
• Magnum 275
• Magnum 310
• Magnum 340
• Magnum MX215
• Magnum MX255
• Magnum MX285
• Steiger / STX 4WD 380
• Steiger / STX 4WD 430
• Steiger / STX 4WD 435
• Steiger / STX 4WD 450
• Steiger / STX 4WD 500
• Steiger / STX 4WD 535
• Puma 165
• Puma 180
• Puma 195
• Puma 210
• Puma 225
• Maxxum 110-140

1. 1

   Check for related 5-volt reference codes (e.g., 1014 or 1015), which would indicate a broader issue with the ACM's sensor power supply rather than just the throttle potentiometer.

2. 2

   Inspect the wiring harness between the hand throttle potentiometer and the ACM. Look for rubbed wires, pinched harnesses inside the armrest pivot points, or corrosion at the connectors.

3. 3

   Disconnect the potentiometer and turn the key ON. Verify that the sensor is receiving a steady 5V reference and has a solid ground.

4. 4

   Check the signal wire for a short to 12V. If the wiring is intact and the voltages are correct, the potentiometer itself has failed internally and must be replaced.

1. 1

   Power Down

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

2. 2

   Access the Armrest

   Remove the retaining screws (typically M4 x 12mm or M4 x 35mm hex socket head screws) securing the right-hand armrest console covers and the throttle grip faceplate.

3. 3

   Disconnect Wiring

   Locate the electronic throttle harness (e.g., harness part 276352A1) and disconnect the plug from the hand throttle potentiometer.

4. 4

   Remove the Potentiometer

   Remove the snap ring (e.g., 12mm external snap ring) or retaining screws (M5 x 16) holding the potentiometer to the throttle bracket/lever assembly. Carefully slide the old potentiometer off the throttle pivot shaft, taking care not to lose the friction device wear pads or bushings.

5. 5

   Install the New Part

   Slide the new potentiometer onto the shaft. Reinstall the retaining hardware and ensure the throttle lever moves smoothly with appropriate friction.

6. 6

   Reassembly

   Reconnect the electrical harness, re-install the armrest covers, and secure the grip/switch face.

7. 7

   Calibration

   Reconnect the battery. Connect the Case IH Electronic Service Tool (EST) or use the tractor's integrated instrument cluster panel (ICP) to clear the fault code and perform a mandatory Hand Throttle Calibration so the ACM learns the new minimum and maximum voltage sweeps.