Actually the goal is to get it to not start so there is something to find while troubleshooting it. Any testing must be done while the problem is occurring. GM has had a lot of trouble with their generators since the '87 model year, but your description of the problem doesn't suggest an intermittent charging system problem. It's more likely, since no dash lights were working, then suddenly everything was fine, there is an intermittent electrical connection not directly related to the starting system. In particular, look in the under-hood fuse box for a large bolted-in fuse and / or a smaller red positive battery cable bolted to it. Be sure those nuts are tight. Follow the smaller black negative battery wire to where it bolts to the body and be sure that is tight and not rusted.
Also look at the battery cable clamps. Those should not be a problem now that they put a new battery in, but it's not something to overlook.
The next time this happens, release the ignition switch to the "run" position and turn on the head lights so some current is trying to leave the battery. Start at the battery and carefully wiggle the cables in various places while watching for the head lights to come on. Do not just tug and poke wildly on stuff. The goal is to see exactly what affects the problem, and you might see a small spark when you irritate the cause.
Tuesday, November 13th, 2012 AT 5:23 AM