punky

So I happen to be one of the unlucky ones where my navi's dimmer controller has failed. None of the backlights on my climate controls are working, even though i've gotten all new bulbs.
I was thinking of getting a new navi screen complete with climate control buttons from ebay, but i need to know whether i'll need a new set of PIN for the new unit? So my question is: is the navigation PIN tied to the DVD unit at the back or the navigation screen? If its tied to the navigation screen, can the dealer give me a PIN without the donor car's VIN #?