Case IH 18259 (518127.03, 518127.04, 518423.03, 518423.04) - ACML – ACML (Armrest Control Module): Throttle2 Position ACML - error state

The control module is detecting an abnormal voltage signal from the secondary hand throttle position sensor (Throttle 2) located on the tractor's armrest. The .03 FMI extension indicates the sensor's signal voltage is above the normal operating range (shorted high), while the .04 FMI extension indicates the measured voltage is below the normal operating range (shorted low or open circuit).

• MAXXUM T4E
• VESTRUM CVX
• Case IH Puma Series (190, 200, 205, 215, 225, 230)
• Case IH Magnum Series (235, 260, 290, 340)
• Case IH Maxxum Series (135 Multicontroller ActiveDrive 8)
• Case IH Steiger Series

1. 1

   Visual & Mechanical Inspection: Turn the keyswitch to the OFF position. Check the mechanical travel adjustment of the armrest throttle position sensor to ensure the sensor is not loose or physically misaligned.

2. 2

   Wiring & Connector Check: Inspect the electrical connectors and the wiring harness between the Throttle 2 position sensor and the Armrest Control Module. Look for damage, abrasion, corrosion, or incorrect attachment.

3. 3

   Pull Test: Perform a gentle pull test (approx. 10 lb / 45 N) on each of the wires in the sensor's harness connector to ensure pins are securely crimped and seated.

4. 4

   Voltage Check: Verify that the fuel throttle position sensor power supply is receiving the correct +5 Volt reference from the module.

5. 5

   EST Monitoring: Connect the Case IH Electronic Service Tool (EST). Navigate to the ACM Advanced Configuration screen and monitor the 'Hand throttle #2 position' or 'Powershift CIH throttle position' data parameters while moving the throttle to see if the signal drops out.

1. 1

   Power Down

   Turn the keyswitch to the OFF position and disconnect battery power if servicing the Armrest Control Module directly.

2. 2

   Access the Armrest Internals

   Remove the necessary bezel screws (e.g., M4.8 x 19mm self-tapping screws) on the MultiControl armrest to access the EDC assembly and throttle potentiometers.

3. 3

   Repair/Replace Wiring

   If the diagnostic checks revealed chafed wires or corroded pins, repair the harness or replace the connector pigtail.

4. 4

   Replace the Sensor/Throttle Assembly

   If the wiring and 5V supply are intact but the sensor fails to read correctly, remove the defective Throttle 2 position sensor/assembly. Install the new throttle assembly and secure it to the armrest chassis.

5. 5

   Reassembly

   Reinstall the armrest bezels and throttle knobs.

6. 6

   Calibration

   Power the tractor on, connect the EST, clear the stored 18259 / 518127 / 518423 fault codes, and perform an armrest throttle calibration procedure to ensure the ACML learns the new minimum and maximum travel voltages.