Case IH 18422 – Cab Controller / Armrest Controller or ICP: Reversible Fan Switch: 'RevFanSw' CAN signal from ICP - error state

A Controller Area Network (CAN) communication error regarding the Reversible Fan Switch ('RevFanSw'). The system is reporting that the CAN signal originating from the switch on the ICP is in an 'error state', which typically means the signal is missing, out of range, shorted to ground, or experiencing an open circuit.

• VESTRUM CVX
• Optum CVX/CVXDrive
• Puma series (140-240)
• Vestrum CVXDrive
• Magnum
• Steiger/Quadtrac
• Farmlift series (632, 742, 935)
• CX Series Excavators
• M-Series Dozers

1. 1

   Inspect the physical Reversible Fan Switch on the ICP for sticking, physical damage, or liquid intrusion

2. 2

   Use the CNH Electronic Service Tool (EST) to monitor the 'RevFanSw' parameter in real-time to see if the state changes from OFF to ON

3. 3

   Check the wiring harness connecting the ICP to the main cab harness, testing the CAN High and CAN Low lines for continuity and ensuring no short to ground or power

4. 4

   Disconnect the ICP harness and inspect the connector pins for corrosion, fretting, or pushed-out pins

1. 1

   Disconnect Power

   Turn off the machine and disconnect the negative battery terminal to prevent electrical spikes on the CAN bus.

2. 2

   Access the ICP

   Remove the retaining screws on the Multicontroller armrest cover or the specific ICP trim panel to expose the underside of the switch panel.

3. 3

   Inspect/Clean Connections

   Disconnect the main harness to the ICP. Use electrical contact cleaner on the terminals. If any pins are corroded, replace the pigtail connector.

4. 4

   Test/Replace the Switch

   If the Reversible Fan Switch is a standalone rocker/button, test it for continuity when pressed. If it fails, pop the switch out of the bezel and replace it. Note: On many newer Case IH tractors, the ICP is a single sealed unit; if the switch fails internally, the entire ICP module may need to be replaced.

5. 5

   Reassembly & Calibration

   Reconnect the harness, reinstall the armrest cover, and reconnect the battery.

6. 6

   Clear Codes

   Connect the CNH EST, clear the inactive 18422 fault code, and run the reversible fan manually to verify the repair.