Just in case anyone interested, most of the time you have to go through a 3rd party, such as the police, to track a vehicle if it happens to have an anti-theft GPS. I subscribed to a service where I can find my truck 24/7 real-time right from my home PC:
GuidePoint Systems - Track your vehicle - Get: directions, road information, Emergency help, Restaurant or hotel reservations, Your cars GPS location
They also let you know when you battery is low on power, a handy service.