It is my understanding that cars that have been outfitted with the Lo-jack system have the transmitter placed in a place you won’t be able to find. The reason for that is that they don’t want the bad guys to find it either. Take the car to a Lo-jack dealer and they probably can tell you whether or not you have on installed.
“Ask your car dealer or the previous owner if the vehicle is equipped with LoJack. If there is a LoJack in your car, you will need to contact LoJack Customer Service at 1—(800)-4-LOJACK (1–800-456–5225) to arrange for an inspection appointment. See owners page for more information.”