Case IH 520619-02 - ACM – ACM: Constant engine speed setting 2 switch circuit fault

The control module is receiving an out-of-range, erratic, or open/shorted electrical signal from the CES #2 button/switch located on the tractor's armrest control panel.

• MAGNUM AFS Connect
• Puma Series
• Puma 175 CVX
• Maxxum Series
• Maxxum 110
• Maxxum Multicontroller EP
• Magnum Series
• Magnum 260
• Magnum 290
• Steiger Series
• Farmall Series
• Compact 35A/40A
• Farmall C

1. 1

   Perform a functional test by starting the engine, bringing RPM above 1000, and attempting to activate CES Program 1 and 2 to see if the button is ignored or physically sticking.

2. 2

   Visually inspect the CES #2 switch on the integrated armrest control panel for physical damage, liquid intrusion, or debris.

3. 3

   Inspect the wiring harness connecting the integrated control panel to the Armrest Control Module (ACM) for chafing, pinched wires, or loose connectors.

4. 4

   Use the AFS Pro monitor or a dealer diagnostic tool to monitor the live state of the CES switch, checking if the signal toggles correctly between ACTIVE and INACTIVE or reads erratically.

1. 1

   Disconnect Power

   Turn off the ignition and disconnect the battery to prevent shorting sensitive armrest electronics.

2. 2

   Access the ACM and Switches

   Remove the necessary covers on the Multicontroller armrest to access the integrated control panel and the Armrest Control Module.

3. 3

   Test the Switch/Panel

   Test the continuity of the Constant Engine Speed switch #2. If the switch is hard-soldered into the integrated control panel (EDC assembly) and fails the continuity test, the panel itself must be replaced. If it is a modular switch, replace the switch.

4. 4

   Clean Connections

   Disconnect the harness at the ACM. Inspect the pins for pushouts or corrosion. Clean the contacts with an approved electrical contact cleaner and reconnect securely.

5. 5

   Reassemble and Test

   Reassemble the armrest, reconnect the battery, and start the engine.

6. 6

   Verify Repair

   Clear the fault code. Bring the engine speed above 1000 RPM, press and hold the CES #2 button for 2 seconds to store a speed, and verify that the tractor maintains the RPM without accelerator input.