Case IH 520616-01 - ACM – Armrest Control Module (ACM) / PTO Controller: Rear PTO engage switch internal failure

The system has detected a mismatch or failure in the PTO switch circuit. The CAN bus signal does not match the hard-wired PTO signal, indicating an internal switch failure, a stuck switch, or a wiring short/open.

• MAGNUM AFS Connect
• Magnum Series (235, 260, 290, 340)
• Steiger Series (500)
• Puma Series (145, 155)
• MXM Heavy Utility Series (120, 130, 140, 155, 175, 190)
• Maxxum Series

1. 1

   Check for companion codes (such as ARM 1039 or PTO 1010) which confirm the armrest controller is recognizing a switch failure.

2. 2

   Perform a Monitor Screen Test using a service tool: Go to the Monitor screen, select 'PTO OFF SW', and toggle the physical PTO switch. If the display matches the physical switch changes, the switch is functioning and the issue is likely in the wiring harness.

3. 3

   Inspect the wiring harness routing under the cab and against the controllers. Ensure wires are not rubbed, loose, or draped in front of the controllers.

4. 4

   Verify that the wire to the controller pin is not shorted to power when the key is off.

1. 1

   Power down

   Power down the tractor and disconnect the battery to prevent electrical surges to the ECU.

2. 2

   Access panel

   Access the right-hand armrest side console / operator control panel where the PTO command switch is located.

3. 3

   Disconnect harness

   Disconnect the 4-pin electrical harness connector from the bottom of the PTO switch.

4. 4

   Remove switch

   Remove the faulty switch assembly by unscrewing the heavy-duty threaded collar to release the switch from the armrest panel.

5. 5

   Install switch

   Insert the new 40mm rounded button profile switch into the armrest and secure it with the threaded collar.

6. 6

   Reconnect harness

   Reconnect the 4-pin electrical connector.

7. 7

   Test system

   Reconnect the battery, power on the tractor, and clear any stored fault codes. Test the PTO engagement to ensure the fault does not return.