Hello, I am new to your forum and also a new (to me at least) owner of a '77 4 speed L-48. I have had it for a few weeks now and it had been running and driving fine, but then I started having trouble with the wiring. First was when the neutral safety switch became unplugged from the harness, no big deal. Then my taillights, which work fine during the day, go out when I turn on the headlights. Weird as they still work fine when the headlights are off, but when the headlights (or park lights) are turned on they just go away. no brakes or turn signals or anything.
Then the other morning came the big one: I went to start it up and when I turned the ignition over everything shut off. The previous night I replaced a fuse that had been missing from the courtsey/dome light/ door buzzer and they all started working fine. The next morning I put the key in the ign., turned it to the on position and all of the lights came on, then tried to turn it over and all of the lights went completely out. The battery is fine, and I assume it is a wiring problem because when I was moving wires around under the dash the lights would come back on. However every time I would try to turn the engine over the problem would come back. Today I decided to go whole hog and pulled the dash completely out (what a huge pain, I don't know if I will be able to get it back in now). After I pulled out the dash I began to unscrew a bolt on the bracket that covers the steering column and the lights magically came back on. I once again tried to turn the key to start the engine (not that it would've because the neutral swith etc. were unplugged) and the lights went out again never to be seen again. Anyone have some advice?

While I'm at it the speedo hasn't ever worked, only starts to bounce at about 55 and the cable looks ok, mabye a little low on grease.

 

Wiring problems are a pain. Get a good schematic and see what is related to the wires you moved and fuse you replaced.

The Speedo problem could be several things. Probabaly the Cruise Control transducer. Make sure the cable is not broken going in or out and that the transducer turns. Try the cable coming out and see if you can make the speedo move by turning it.

 

I was told once that if the electric component works but not how it's suppose to, start with rechecking all the ground connections. These cars are fiberglass and proper grounding is essential.

BTW welcome to the insanity.

 

You may be in over your head. That could cause you much more expense than just cutting your losses and taking to a professional. But enough preaching. I agree that the problem is most likely a faulty ground. I would start by undoing the fuse to the interior light. Could be, that it was removed to cure a slow drain on your battery. Do you have an amp meter? Learn how to use one and you'll be on your way to understanding all 12 volt systems. Honestly, I wish I had more time to learn this stuff myself. I understand the concept of wanting to do it yourself. Just know how to balance that with your safety and the almighty dollar. Good luck and welcome.

 

WELCOME to the corvette world
and all the problems that come with it

 

Thanks for the input, can you guys give me a quick rundown on some of the grounds that might affect the ignition? Where are they located? Is there one on that steering column bracket that I cannot see? It's the one that is on top of the column back against the firewall by the top of the dash?