wiring problem

Hi all, I have a problem with my wiring and hope you can help. I just installed a 94 motor in a 93 2500. I changed the IP from electronic to manual. No problem there. On the wiring harness that is on the firewall I have a purple wire sticking out. I think it may have got pinched and cut in half. It comes through the harness right behind the fuel filter. When I turn the ignition on it has power. I found out that, by accident that if it hits a ground it blows the fuse to the ECM/Ignition. I don't see where this wire goes. I know this is long, but i'm trying to give you all the info. Any help is appreciated.