The electrical system is my weakness, so bear with me as this might be very elementary.

Everything has been working awesome, until Saturday I went out to adjust my timing. I have absolutly no power at my ignition, dome light, etc. I tested my battery, and it's fully charged, and power is getting to my alternator fine. I have no blown fusses at my fuse panel under the dash. My grounds look good to me from my battery.

What happened? What should be the order of tests I need to do to troubleshoot this problem? Is my starter or coil fried? I just don't understand the electrical system good enough to really analyze this, but I want too. Thanks!

 

The same thing happened to me, and mine was just a bad ground wire to the block. Make sure all of your battery cables are in good shape. They are the cheapest and easiest things to replace, or just wire-brush, and hook back up. Hope this works... if not, I would be looking for help too.

 

Is there a way to test the ground to the block? Or just buy a new one and install?

 

The first thing I would do is turn the headlights on and just wiggle the ground wire to the block. If they flicker, you found your problem. I would then take it off and wire brush the hell out of it (both the wire and the mounting surface on the block and the battery). Hope this helps.

 

The engine/firewall ground came to my mind first as well. As far as checking it, it may be as easy as loosening the two fasteners, and tightening them back up again. I'm not sure about '70's, but most grounds are braided straps. As long as you can pull on it and it doesn't break in two - I'd think it's alright.

One other thing to check is the connection of the main harness where it passes through the firewall. I would unplug it and plug it back in - just in caseof a bad/weak connection.

 

Also check that your battery cables are tight at both ends and not corroded. Beyond that and the ground strap, it starts to get more involved.

 

Take your DVOM and put it on OHMs and put the red lead on the block and the black on the - batt post. it should read 0.00 or close to that, if it reads OL or very high thenyou need to ground the block

 

Thanks everyone! It was the ground to the block I grabbed at the block conection, and tried to wiggle it around, it sparked, and the headlights turned on.

The bolt between the ground and my block is pretty rusty, I'm guessing that rust isn't a good connection? Well, obviously. I'll clean off the connection to make it more reliable.

Again, thanks everyone...