On my 77 Corvette when I put on the high beams and wait a few minutes all the headlights start flickering on and off. Could that be the highbeam switch only that is bad? Or could it be something else? My headlights only flicker when I put on the highbeams other than that the headlights work fine.

 

Your high/low switch is fine. It's the breaker in the headlight switch doing it.
On low beam your only running 2 headlights. On high beam your running all 4. The circuit breaker in the headlight switch isn't handling the load.
Join the club and add relays.
Please go to Mad Electricals web site. Go to there tech pages. Read how simple it is to install 2 relays and take all that load off your 47 year old switches.

 

So your saying that all of us that own a C3 have this problem? That's how it came off the line? Wow! I believe you.

 

The issue is that perhaps you have installed more modern headlights using more power, or simply that the circuit breaker in your switch if original has grown weak with age. 47 year old wires now have gotten a great deal of resistance in them from natural corrosion. Or, a replacement aftermarket headlight switch. These are notorious for having a weak breaker.
bottom line. Install relays. Switch then only needs to trip a relay. F all power to trip a relay. Relay then supplys power to the lights. Brighter lights. Almost no load on your old switches. Win, win! And DONE!

 

As I said. Go to "madelectrical.com" go to there tech pages. On the top. Read. They explain it so us dummy's can understand. They also sell bits if you don't think you can DIY it.

 

see these 2 relays. They were the first electrical upgrade my car got. Back in the mid 90's. I found going down the very dark Northwoods Wisconsin roads with my lights on high beam. They would suddenly just go out!
Completely! In a forest! With virtually no moon light. Just pitch black!
There was no internet that I knew about back then.
I asked my No Brother Good-In-Law. Who knew a little bit about Chevys, what ya think. He told me about the circuit breaker in the headlight switch. Seems it's not just a Corvette thing.
I had the intelligence to install relays.
Later, the internet came along. Seems everyone and his dog installs headlight relays on old G.M. vehicles and old fords.
This is a super common problem. Welcome to the club.

 

Thank you for the help. I see you have it wired to your alternator.

 

NO YOU ABSOLUTELY DO NOT! My mother didn't raise idiots! My headlight relays nor anything else is wired to my alternator.
I have a strip fuse panel mounted on the forward side of the passengers footwell. A motorcycle sized cable from the positive battery cable on the solenoid to the fuse panel. The panel fuses headlight relays, electric fans , etc. My EFI is straight off the battery with a fuse in the battery box.
DO NOT run your headlights off the alternator! Once again, PLEASE , go to Mad Electricals web site. READ the tech pages on headlight relays. And while your there. Check out the articles on alternators.

 

Dug out an old photo of my fuse panel with the cover removed.

This is where my headlights get there power. Note the Harley battery cable supplying power to the panel. Start motor is inches away. The alternator in my previous post is just because that's where the alternator is. In NO WAY whatsoever are my lights connected to such dirty, fluctuating power!

 

I DIDN'T SAY YOU WERE AN IDIOT!! CALM DOWN BIG BOY. It just looked like that in the picture. JESUS CHRIST!

 

Hang in there Gary. I was just driving a point home. I'm actually a pretty calm person.

 

you’ll know if I’m calling you an idiot trust me. So how did you wire this thing up? Is it easy to do? Can you just tell me how to do it without me doing a web search?

 

Well, it shouldn't be to hard to just put Mad Electrical in Google. But yes I can tell you how. I just need to pull out the basic relay wiring. Basically, cut the high and low beam wires going to the headlights on the left inner fender. That's why you see almost everyone put them right where I did. On the left inner fender. The wires from the high/low switch become the signal wire to the relay. The wire to the high or low beams become the power out of the relay. Obviously you have a ground wire. Tie it in or run to a good ground. Power from battery cable on the solenoid, fuse, about 30amp should be fine. Run new power wire up and around the back of the engine with the rest of the wires, under the brake booster and to the 2 relays.
I'll draw up a basic schematic, although you could just look at Mad Electricals Web site. Which you really should be doing. They spell out old car wiring so us normal people can understand!
you go to your favourite auto parts store. Purchase 2 standard 30 amp relays. I recommend Bosch. And some 1/4 inch female spade connectors, you'll need 8. About 2 yards of 10G wire and a 30 amp fuse holder with fuse.
In the meantime, I'll make up a simple drawing to show you what wire goes where.
I believe Richard 454 a member here who does electric headlight kits also makes a plug and play setup. Correct me if I'm wrong Richard.

 

OK, did ya pick that stuff up yet? I forgot to mention, you'll need a ring terminal for the battery cable stud on your solenoid. (3/8th's ring) Disconnect battery. Then connect wire to ring terminal and terminal on main battery post on starter solenoid. This is easier than going all the way to the battery and more than good enough. Fuse should be just inches from stud. Run power wire up with the starter wiring, over and behind the distributor, under the brake booster to your relay mounting location. You will tee this power wire off to supply power to each relay, post number 30. If you look close on the bottom of a standard square relay, you will see numbers next to the spade terminals. If your like me, put on your readers. OK. So, new power wire run up to both relays. Tee'd off and power to each relay on the number 30 terminal on each one.
let's look at 77 headlight wiring.

From the factory manual. We can see that high beam is a light green wire and low beam is a tan wire. Open up the tape wrapping on the harness along the left inner fender. Find these 2 wires. You can test they are the correct wires with a test light by reconnecting the battery and turning on the headlights and switching between high and low beams. Making certain you have the correct wires. Cut them. The light green will go to one relay. The tan to the other. One will be a high beam relay. The other the low beam relay. The tan or light green depending on which relay, from the switch, goes to terminal number 86. The tan or light green wire going to the headlights will connect to terminal number 87. Terminal number 85 needs to be connected to a good ground. One relay needs to have both tan wires the other both light green wires.
like this.

once you wire this up, hardest part is running the new power wire up from the starter solenoid. Your lights will be brighter and you won't keep losing your high beam anymore.
be certain to test wires, there is a brown one in that harness that goes to the alternator that could be mistaken for the tan headlight wire.

 

As an alternative to all this you can do what I did and install brighter LED headlights that draw half the current. (It also helps with the load on the alternator) If you do go that route please make sure you get the proper type of housings and led bulbs that are designed to work together so you dont blind everyone on the opposite side of the road.

I bought the all in one style led lights which have the amber /white halos that alternate with the turn signals I like them for my restorod but they are not for everyones taste.

 

There is a reed switch inside the headlamp switch which controls current. If you've installed halogens or other high wattage bulbs (more than stock) these bulbs will overcurrent the reed switch (heat) causing it to open. Once it cools it closes and your light come on. This will cycle as long as the current is flowing through the reed switch. I see people have mentioned installing relays. This takes that high current out of the switch.

 

My experience has been low beams turning off, but still have high beams. That negates the headlight switch, and makes it the high/low beams dimmer switch.

 

It's perfectly fine to connect your headlight relay power to the alternator. Speed Directs "Nevernight" harness upgrade kit does it as well.

 

Also the output of the alternator is the + side of the battery. They only thing that is different between the two points is wire. With that said I always try to wire accessories directly to the battery +/_ .

 

Not necessarily Roy. It could just be your old wiring has more resistance in the low beam wiring. And at the end of the day. Putting in relays will take all that load off both the headlight switch and the dimmer switch in one swoop as they say.
Bottom line. Relays should fix your problem as well Roy.