PCM fuse blows immediately with the turn of the ignition switch. The starter never starts to turn. It happened once before. Ford dealership was not able to find problem. I replaced the fuse a few times and then it just quit blowing for several months. Now it blew again and it blows every fuse that I put in it as soon as I turn the ignition key switch. I realize that there is probably a short, but need some advice concerning where to look and/or how to diagnose where the short may be.

Please help.