Case IH 18301 (517675.02, 517675.03, 517675.04, 517675.07, 517675.13) – ACML (Armrest Control Module Local): Autoguidance Switch ACML - error state

The control module is detecting an abnormal condition from the autoguidance engagement switch circuit. This can be caused by a short circuit to a high voltage source, an open circuit or poor electrical contact due to contamination, or voltage fluctuations triggering a false error state due to overly sensitive software parameters.

• MAXXUM T4E
• VESTRUM CVX
• Puma (150, 165, 200, 220)
• Maxxum (135, 145)
• Optum
• Vestrum
• Magnum
• Axial-Flow (8250)

1. 1

   Diagnostic Display Check: Go to the settings/diagnostics page on the cab display. Locate the Autoguidance switch input and monitor the voltage/state both when the switch is at rest and when it is pressed.

2. 2

   Switch Continuity Test: Use a multimeter (ohm meter) to test the switch itself for proper operation.

3. 3

   Harness Inspection: Inspect the wiring harness running from the switch down to the control module. Look specifically for crushed, pinched, or damaged wires, which is a known routing issue on these machines.

4. 4

   Connector Check: Inspect the connectors for poor electrical contact or contamination.

5. 5

   Software Verification: Check the current software version of the ACML. Older software versions had a highly sensitive fault detection time (50ms) that caused false error codes from minor voltage fluctuations.

1. 1

   Repair Wiring

   If the harness is found to be crushed or shorted, repair the damaged section of the wire. Reroute the harness slightly to prevent it from being pinched by armrest components.

2. 2

   Clean Connectors

   If electrical contamination is found, clean the connector pins with contact cleaner and apply dielectric grease.

3. 3

   Replace the Switch

   If the switch fails the multimeter continuity test, replace the Autoguidance switch assembly.

4. 4

   Update ACML Software

   If the switch and wiring are intact, the issue is likely software-related. Have a dealer flash the ACML to software version 3.1 (or newer). The revised software relaxes the error code parameters by increasing the detection time from 50ms to 500ms, which prevents voltage fluctuations from triggering the error state.

5. 5

   Replace the ACML

   If the module itself has suffered an internal hardware failure and cannot read the switch input after a software update, replace the ACML ECU.