Hi, new member. Owner of a 2005 Cayenne with a couple of issues. Four Wheel Drive Faulty message and fan runs constantly while engine is running and for about 15 minutes after engine has been turned off. Cars temp is fine and coolant level is good.

I've read the four wheel fault could be servo motor... before I spend the money on the part is there a way to confirm this? check for voltage at the motors connector or at the consoles switch maybe?
Thanks for any help in pointing me in the right direction.