I did look (here and in my car's manual) but didn't see anything on upgrading a nav. system. I am thinking of getting a 8.1 from Sewell's or maybe a used 7.1 from some place if I can. I have a 2/3 gen nav. system w/3.1 installed. Is it just take out old disk and put in new disk to change? Or does the dealer have to do it? Or can it be done, but must follow a specific procedure?
Thanks for any help in advance.

 

I did the 7.1 update because our subdivision wasn't in the 2/3 gen. It was just a disc swap. There was an installations that ran the first time and that was it.

 

When you update from version 1 (and maybe from ver 2) data, the disc will update the OS. This provides a few new graphics.)
All other disc changes simply provide new data.
As for procedure, to be perfectly safe, do everything with the engine running, (the screen will say "no disc detected" during the change) and don't turn off the engine until the NAV is reading the new disc. The whole process should take about 3 minutes, if you go slow.
Keep the old disc for emergencies, as the system will read old discs newer than 2.1.