1999 Buick Century Short in Starter Wire

1999 Buick Century

I have a '96 Chevy Lumina with a '99 Buick Century engine in it. The car would not start one morning. There were no lights, chimes, nothing. It was completely dead. We jumped it, let it run for 30 minutes, turned it off. The next morning it started fine, BUT when I went to turn into a parking lot, it again died with no lights/power/nothing. I let it sit for about 5 minutes, then it again started just fine. Have also noticed that the emergency brake light stays on when it is going to act up like this. When it is completely dead, if I alter the way I try to start it (jiggle the ignition switch, turn the key faster then slower), I can usually get it to start, but it will die whenever I slow down (have to keep it above 2000 rpm's). Yesterday, it drove fine to the Auto Parts store. I had them check for trouble codes, and there were none. When I went to leave, it was again compeletly dead. The Auto Parts Store empolyee popped the hood and jiggled the start wire with the key in the ON position. The dash lights flickered on/off as he jiggled the starter wire. When he had it in place, all lights were on and the car started fine. I am a weekend warrior when it comes to repairing cars. So. How do I replace the starter wire?