I have a simple GPS fix that worked for me. After posting and sharing in other forums this fix has also worked for many others who were frustrated with their GPS' not working, not locking onto satellites, and their phones acting erratically while navigating. Although this method seems too easy to be true, trust me it works and many people have confirmed that this method worked for them too and are now happy that their phone has a functional GPS and in some cases improved call quality.
I as well as many others performed many of the other fixes such as flashing back to stock, performing numerous battery pulls, using aGPS patches, making numerous edits to the gps.conf file, reprovisioning our phones, checking different ROMs, uninstalling/reinstalling Google Maps, clearing data for Google Maps and Google Service Framework, and so on. So before you do all of that please give my method a try.
I discovered this simple fix when I was trying to perform one of the other GPS fix procedures. The procedure required me to pull my battery. I noticed that when I removed my back cover the back frame that has all the screws (10 total) was slightly loose on the left side. Once I tightened them all my GPS worked immediately! Like I said, this method has been tested by many people and most of them report great success just by tightening their screws. If this method works for you you'll also notice that in addition to getting faster locks your navigation will work and won't drop your GPS signal.
Like I said it may not work for everyone but I would recommend that if you have a Samsung Galaxy S III definitely check the back frame of your phone and make sure you tighten the screws and make sure everything is secure. You too should now be able to achieve GPS locks consistently.
I hope this helps. If it does, as it has many others, please click thanks.