Hey guys. I recently replaced my brake booster on my El Camino. While working on it, my interior lights kept flickering and sometimes theyd go out completely. I ignored it and got a flashlight. After I was done, I noticed my battery light was on, even with the doors closed and ignition off. I scratched my head and hit the ignition. Nothing. No headlights, tailights, starter, nothin. Just my battery light works? So I messed around a bit and figured it might have something to do with the wiring from my tranny I recently removed. I touched a ground cable that was attached to the firewall to the engine and it sparked. WHAT THE HELL?! MY FIREWALL HAS POWER?! Sure enough, everytime something metal touched my firewall, it sparked. I talked to a guy who knows a thing or two and he said my terminals might need cleaned. The same thing has happened to him. So I wire brushed everything from the battery to the solenoid. Nothin. Whats going on???!!!
Let's think about this logically. First of all every voltage has a positive and a negative side. If you touch the two together you can get a spark. OK. Everyone agrees so far.
The battery has a positive and a negative terminal. Again, we agree. The battery's negative terminal (big wire from battery) gets attached to the engine block (somewhere).
The battery's positive terminal (another big wire) gets attached to the starter solenoid, the alternator, and the fuse box. So far everything is OK.
Normally the engine block has a ground strap that attaches to the frame and another that attaches to the firewall. That makes the entire vehicle be at ground (negative) potential.
Now for the problem.
It seems your firewall is at the positive potential. In order for the firewall to be at the positive potential the ground strap must be missing and a positive wire has been inadvertently connected to the firewall or a positive wire has been shorted to the firewall.
The first thing to do is find out which wire is shorting to the firewall. Then you need to add a ground strap from the engine or frame to the firewall. You have a potential for a fire on your hands, not to mention damage to electrical components.
A voltmeter and/or ohmmeter will be a good tool to use.
If you need more advice, just ask.
Jack