I have an '02 grand cherokee with a 4.7. This little truck ran perfect until I came home one night a few weeks ago and parked it. When I got up in the morning it would not start and never has since. It will turn over but makes no attempt to fire or start. The gauges are dead (although they work fine during testing), and the obd 2 port does not get any readings. Apparently it is also dead. The no key or key with a circle and a line through it is on and stays on (not blinking). So I am assuming the security system has shut everything down or one of the control modules fried, but I can't figure out how to tell which thing has gone bad. Do we really have to just start blindly replacing these expensive parts until I accidentally hit the right one? I have tried starter fluid and have replaced the cam and crank position sensors with zero effect. Still crank no start. If anyone has any ideas it would be greatly appreciated.