Case IH 18421: "RearAutoPTO_Sw" CAN signal from the ICP in error state

The control module expecting this data is either receiving an invalid, corrupted, or missing CAN message from the ICP regarding the physical position of the Rear Auto PTO switch.

• VESTRUM CVX
• Case IH Puma Series
• Case IH Magnum Series

1. 1

   Check for other codes indicating a total loss of communication with the Instrument Cluster Panel (ICP)

2. 2

   Monitor the switch state via the tractor's diagnostic menu (e.g., channel d49 in Puma/T7 models) to see if the controller registers the switch toggling

3. 3

   Check for related physical switch faults, such as code 5042 (Rear PTO management switch – stuck closed)

4. 4

   Inspect the CAN bus wiring harness and connectors between the ICP and the main controller for opens, shorts, or corrosion

1. 1

   Power down the tractor and access the Instrument Cluster Panel (ICP) / Armrest console.

2. 2

   Disconnect the main harness to the ICP and inspect the pins for pushed-out terminals, moisture, or corrosion.

3. 3

   Test the physical Rear Auto PTO switch for proper continuity when toggled.

4. 4

   If the switch tests good but the CAN signal (viewed in channel d49) remains in an error state, the fault likely lies within the ICP's internal CAN broadcasting circuit or the CAN bus wiring.

5. 5

   Repair any damaged CAN wiring. If the wiring is intact and the switch is integrated/faulty, replace the switch or the ICP assembly as required.

6. 6

   Clear the fault codes and verify PTO operation.