Well i was under my dash looking to see why my speedometer wasnt working and i looked behind the fuse box and the wiring harness was loose..well i wiggled it a little and then i heard a few popping noises like fuses blowing but nothing blew and now the truck wont turn over...I was wondering if these trucks have some sort of security system that would keep it from starting..I never thought to unhook the battery yet cause i wasnt planning on taking anything loose

 

There are a couple of big fuses located next to the battery on the firewall. One is for the alternator and one is for the power distribution box. You might check to see if the one for the power distribution box is blown. It is a big fuse - I think 175 amps so be sure to disconnect the battery when checking this one.