Ok so you do need to flash a new ROM to get your GPS to work try reading these
http://wiki.xda-developers.com/index...name=HTC_Titan
This is the wiki loots of info here
http://forum.xda-developers.com/showthread.php?t=363431
This ones the official GPS thread
the links within these pages will help you actually flash but those are the tutorials.
READ VERY CAREFULLY, YOU ARE RESPONSIBLE FOR ANYTHING YOU DO TO YOUR DEVICE
so read until your eyes hurt because theres alot of ways to brick your phone.