Without wifi, the GPS is not working on my TC 970.
I tried operating it many times in open space on clear days for about 30 mins or so.
But every time it says "Error occurred, data connection needed".
The gps requires a data connection to find a location with google maps. So you can set your route while connected to wi fi and then it will get you there.
You need to go into Maps>settings>labs and check cache maps. (i think thats it)
There are navigation apps that claim to work without a data connection. sygic and navfree usa are a couple you could try.
The GPS should find where you are while away from wi fi. It just can't find where you want to go. It would be the same with any wi fi only tablet.