was having same problem
Hello fellow GNex users having the GPS issue.
I was having a GPS problem as well where when using Google Maps or Navigation, the GPS status would say 'searching for GPS' forever.. maybe after 10 minutes it would get a lock and operate normally after that.
I downloaded an app from the android market called GPS Test to try to get some better idea of what could be going on.
When I ran the app, I noticed my phone would pick up a few satellites (satellites in view) usually 4 or 5 satellites, but it would never use them, they would just appear as in view without being used for a location, and the GPS test app was never able to report my location. From within the GPS app settings I was able to clear aGPS and update aGPS, but the same behavior would reoccur where the satellites would be in view but would not be used for location.
I tried toggling Wi-Fi, clearing out other location methods, and even going into airplane mode to use GPS only, but same behavior.
What I finally did was clear aGPS once more and then immediately power off the phone, pull the battery, wait a couple minutes and then replace battery and power back on.
Upon going back into GPS test, I did an update aGPS, and then I started to immediately pick up satellites and use them for location. Toggling all the same data connectivity settings (Wi-Fi, location using towers, airplane mode etc) I was continuing to get the same positive response.
I have tried to use google maps and google navigation again and am getting near immediate GPS locks. Comparing this to my Nexus One, the lock is much faster and with about the same accuracy.
This seemed to solve my problem for now, I hope it might help anyone else.
Phone information:
Verizon Galaxy Nexus
Stock Android ICS 4.0.2 Build ICL53F