Towards the beginning of Terminator 2 Judgement Day, when the T-1000 finds John Connor's address, how does he actually find him? During the year, of which the movie portrayed, there was never any GPS. Even the computer he typed the address into, did not seem advanced enough, to have a visual screen showing route by route directions.
In the movie itself, there is no indication of how the T-1000 was able to find John's house. However, the T-1000 obviously knew his name, age, and the city in which he lived, among other things. It's memory was stored across its entire "body", and was apparently quite extensive.
We don't know whether the computer that the T-1000 used in the police car has GPS capability, but the movie takes place in 1995, and GPS was adapted for civilian use in the following year, so it is at least possible that the police in a major city like Los Angeles would have had access to it a little earlier than civilians did. However, the T-1000 wouldn't need GPS if it had been provided with maps before it arrived in 1995.
We also know that the T-850 in T3 was programmed to make himself resemble the Terminator from T2 so John would recognize him.
The TX in T3 was also programmed by Skynet with all sorts of data about her targets - including photos and DNA samples - and relevant technological information, as these images, showing her HUD, demonstrate:
In this first image, note the text display on the right- "Location Proximity Ratio". This sort of information would be very handy to the T-1000.
It seems quite probable that Skynet uploaded maps of Los Angeles in the mid-90's into the T-1000 before he was sent back in time. This would make perfect sense, since it was programmed for all kinds of other things, like how to interact with humans, how to drive a car, fly a helicopter, ride a motorcycle, use old fashioned firearms, etc. None of these skills would be useful in a post apocalyptic future, but the T-1000 had to learn them all for the sake of his mission.
If Skynet could provide the T-1000 with all this other information, it could certainly provide a map of the city as well.