Harry's 81 C3

1965 Electrical PROBLEMS... Drove my 65 VERT all day w/o issues.... Took her for a spin after dark, Low beams, then I depressed the HIGH BEAM button and drove for another 5 miles and just as I got home the car completely died... A COMPLETE BLACKOUT, nothing electrical worked, not even a clicking starter sound... NOTHING.... I switched back to low beams and connected my trickle charge... 30 minutes later I get a starter clicking sound...
Could there be a short in my dimmer switch? Something ate up all my juice... What's up with my BLACKOUT?

Frankie the Fink

Measure across the battery with a multimeter with engine off - you should see a voltage of around 12.4V or so, start motor and measure again at fast idle....if the charging circuit is working you should see 13.8V or a bit higher.

There are two "bulkhead" electrical connectors near the master cylinder in the engine bay on the firewall. CAREFULLY pull those off without breaking the clips holding them together; one is the headlight harness and the other the engine bay harness - look for corrosion, pushed in or bent pins, etc. Fix any problems found and spray quality contact cleaner like DeOxIT liberally then reconnect and test. The main "red wire" power lead for the car is shown with the red circles. This assumes your battery is good and battery/starter connections are good and corrosion free.

65GGvert

Almost 100% chance the problem is in your bulkhead connector. The horn would still work if it worked before, but you may not have tried it. Everything else in the car goes dead when you lose connection at the inside (closest to centerline) of the two bulkhead connectors below the master cylinder. The uppermost left pin has a large red wire feeding all voltage from the engine compartment to the cabin, via the fuse box. If you carefully remove that inside connector, check both sides of the disconnected plug for corrosion or the pin pushed into the plug so that it is shorter than the others. I'll attach a picture of a really corroded on so you'll know what you're looking for. Disconnect the battery and clean those pins with a brush like a toothbrush or small wire brush and some contact cleaner (or alcohol if you can't get cleaner). The plug has two small plastic clips that hold it together, be careful not to break the clips or you will create a possible loose connection that will require more involved repairs. If your car is still not getting power, wiggle that connector with your headlights on and see if they flash or come on. If so, you know you're in the right area.
While a bad battery or bad cable connections can cause you to lose power, it will not usually shut the car down while running. I feel very sure that your problem is the red wire. If you Google "corvette forum, red wire" or "corvette forum, C2 loses power", you'll find dozens and dozens of post about this same issue that were fixed by cleaning the contacts on that plug. Slight possibility that it could be further in with a corroded connection on the fuse box where the two red wires tie together on the back side, but not nearly as likely.
Here's the picture of a really bad one:

65GGvert

And here's a picture of where they are located with the master cylinder out. In the square below the driver's side hood latch.

65GGvert

That's funny Frankie, I didn't think you were up this early. You posted while I was looking for a picture of the connected bulkhead plugs. Really odd that we posted the same two pictures. Now I feel bad because it just looks like I copied your post. Oh well, since we both gave the same answer it will make it easier to work with.

Frankie the Fink

No worries - with two strong recommendations of the likely trouble area this owner should be doubly incentivized to look in that spot!

It would be nice, if when this happens, drivers would try the horn immediately but -- after all, its kind of a panicky situations; especially at night...