You are referring to the navigator app with free maps right?
If you switched off your data, & use your GPS, you need to find a place outdoor to capture the GPS satellite first. If you are indoor, it is almost impossible to locate where you are.
Last Dec, I was in US and use app navigator. With the free map, it was fairly accurate without the data network. I bought the map & you can see more things around you.
Of course, at home we usually use Google map or the singapore street directory app, with the data network switch on.
Bob