A little back story...

I replaced my distributor with a new stock replacement one. Fired the car up, no issues, idle was right where it should be, I connected my timing light, (power to the alternator post and ground to the engine block), as soon as the ground was connected the car died, turns out the ignition module in the new dizzy went out. I installed the ignition module from the old dizzy into the new one and it fired back up, my timing was off enough that the rpms were high so I shut the engine off, connected the timing light the same way as before. When I went to start the car, the starter hit 3 times then everything electrical in the car died. I haven't been able to get anything to work since then.

I let it sit all winter and when I measured voltage there was 13.6 volts (measured at battery, starter, alternator). Tried to start it and nothing happens, but the voltage drops to 2.5 volts, measured at the same 3 places. When I unhook the cars harness from the lead coming off the starter, it goes back to 13.6. Everytime I reconnect the cars harness it goes back down to 2.5 volts. I pulled all of the fuses out of the fuse box and it raised the voltage to 4.5 volts.

Any ideas? I'm at a loss here. Almost willing to leave the battery connected and let it sit, and let the insurance fix it when it burns down.

 

What year?
late C3's have a connector behind the pass head at the firewall that connects the main harness to the starter extension harness. Its a white molex connector and they burn frequently.
I would follow the fuse links from the starter to the main harness and see whats up.

 

It's a 1980, 350/4 Speed.

That's the connector I was talking about when I said I unhooked the cars harness from the starter leads. the connector looked good. All power and grounds that I could see looked good and checked good when tested for continuity.

 

I also have a 80 4 speed!
When you measured the voltage and got 2.5, was that at the battery terminals? I think I would charge the battery and do a fast load test on it. I know you listed the voltage at 13.6 (12.6 is normal), but if the battery sat all winter without a trickle charger, you could have a battery problem.

 

I had it on a float charger all winter, I did have a dead battery at the end of last season, but its been plugged in for a few months now.
The voltages I mentioned were checked at the starter, alternator and battery, all 3 locations matched each time.

 

I hooked up the battery from my other vehicle. I was able to get battery voltage at the starter and alternator, but when I turned the key, nothing happened. The starter wouldn't crank and nothing on the interior powered up.

I guess I'll track down a wiring diagram and start going wire by wire. I'm almost wondering if the ignition switch went bad on it.