MerpsMom, Use GPS satellites and/or "Use Wireless networks" needs to be checked (Menu->Settings->Location & security) for any Android phone in order to use an app that requires GPS or location referencing (e.g Google Navigation, Google Maps, Telenav; GPS exclusively on running apps like Runkeeper, Endomondo or Golf apps that track the golfer's shots for every hole). Additionally, you can turn your GPS on/off by swiping down on the notification bar - it will be the last icon on the right corner. Google Navigation (blue arrowhead icon with Navigation label; includes turn by turn voice navigation) uses and requires your phone GPS exclusively (click on the Maps label on the top right to activate Navigation) while Google Maps will prompt you to turn on GPS and/or wireless networks if both are not set (Note: Navigation can be selected within Google Maps).
As Netcat posted earlier, it is advisable to download and install GPS Status & Toobox (EclipSim) from the Android market. GPS Status & Toolbox can reset the phone's GPS cache and download the aGPS almanac data which is very handy if your phone is having an issue getting a GPS fix (within 10 seconds if not a few minutes).
Here is the market link for the app:
https://market.android.com/details?id=com.eclipsim.gpsstatus2&feature=search_ result#?t=W251bGwsMSwxLDEsImNvbS5lY2xpcHNpbS5ncHNz dGF0dXMyIl0
GPS Status & Toolbox allows you to reset the GPS cache and download aGPS almanac data through the following process (Menu->Tools->Manage aGPS Data, select 'Reset' and then repeat the steps and select "Download' to download the aGPS almanac data) to help your GPS get almanac data on the satellites. Here is some information about it:
Before I plan on using the GPS on my phone for running (Runkeeper) or Navigation (Google Navigation with the blue arrowhead app icon), I always turn on the phone's GPS and then launch GPS Status & Toolbox first to ensure that I get a good lock on my phone (usually 1 - 6 meters of error).
I have a very high success rate of getting a good GPS lock within 10 seconds, especially on a clear day, whether indoors or outdoors and I don’t find it much of an inconvenience to turn on the phone’s GPS, launch GPS Status & Toolbox and confirm a good GPS lock, exit out of the app and launch the Navigation app (Perhaps you can turn on your phone’s GPS and use GPS Status to get a lock daily to keep the almanac data current on your phone).
Under Settings->GPS & Sensors ->Auto-download AGPS data you can select to automatically download the latest data when GPS Status is run (download if older than 1 hour, 6 hours, 1 day, etc.). aGPS data age is displayed in the lower left corner of the app until you get a GPS fix.
Some users have also toggled the Sensor Filtering to “No Filtering” instead of the default “Weak” filtering to get a quicker GPS fix. Here’s a thread about this:
GPS slow in Google Maps after OTA update [Archive] - xda-developers
On the rare instance that I’m having a GPS lock issue, the final solution for me is to reboot the phone and repeat the process of getting a GPS lock again, and fortunately it has always worked for me. Some users have also recommended going to Menu->Settings->Applications->Manage Applications->All tabs and clicking on "Google Maps" and "Network Location" and clearing their Cache data.
GPS gives you the best accuracy and is the setting that is required especially if you're apprehensive about turning on "Use Wireless Networks". You can switch both GPS and Use wireless networks off if you're not using a navigation app to conserve battery life and make sure you use the <back> key to completely exit out of your navigation app (or any app) and properly exit out of the app instead of having it run on the background unless you intentionally want to do so. I hope this helps.