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i made a thread about this recently but my headlights have decided to no longer be with us. I replaced the switch and i relocated the ground to a cleaner surface that is bare metal and boom still nothing. When i pull the switch everything comes on literally every light but the headlights. They pop up and do what they should but the bulbs are not lit. I checked the filaments in each bulb and i always checked to see if power was making its way to the socket it was not. I have no idea what to do now. Has anyone seen this before??? And what was the cure to it??? Any and all help is appreciated i wanna drive my baby LLOL.
OK, back up. The power wire for the headlights is a separate wire out of the light switch that goes to the high low switch.
What year car are we working on here? High low switches can be on the floor, in the column, knowing the car would help!
But, if all your other lights are working. Then you are getting power to the light switch. But is it going through the switch to the high/low switch?
If it is. Than is power coming out of the high/low switch? If it is, than is power getting through the bulkhead connection at the firewall?
This is really simple!
Get to the switch! Is power coming out of the switch?
NOT the bloody tail light wire! The headlight wire! What color is it? I don't know! I don't know the year of your car!
Here's my attempt at helping you. This is from the 1977 Factory Electrical Trouble Shooting Manual.
As you can see. In 1977. It's a light blue wire from the light switch to the high/low switch. (Dimmer switch) then tan and light green wires from Dimmer switch to the headlights. Connection C115 is the bulkhead connector on the left side of the firewall.
Light green is low beam, tan is high beam.
This is so Bloody simple! The only hard part is getting to the switches and wiring to test it.
If you do not have a Factory, Electrical Trouble Shooting Manual for your car. GET ONE!
It will save what's left of your hair!
OP you have 2 power feeds to the Headlight Switch...
1977-1979 wire colors are Red & Orange
Red wire Circuit B and a Orange wire Circuit A
Circuit B is a direct feed from Fusible Link B near the starter Solenoid.
Circuit A seems to be working as your dash and other lights are working.
If you have no power at the switch (At All Times) on the Red wire (Circuit B) then start working your way back to the starter solenoid...
There is a (4 or 6) wire connector behind the distributor that can be suspect so check that too...
Okay guys i have a 1979 corvette with the sour speed and an l82 sorry i didn’t specify. Wiring is my worst fear i hate it with such a strong passion because it sucks to me so much. So im super sorry but a lot of this stuff doesnt make much sense to me. If someone could send me either a YouTube video where i can watch someone do it. Or a very nice step by step guide that would really be appreciated. I mean the switch is brand new i replaced it two days ago so i dont know why it would not be sending power out of it? I tested the wires at the headlight the green one im not sure if that was the right one to test or even if i did it right. When it comes to wiring as you can see i really am lost. Any help is welcome videos or step by step guides In baby terms please LMAO. It sounds simple i just have barely any wiring knowledge im sorry for my dumbassery.
Don't be sorry, this is how you learn.
I'm not a wiring expert by any means, but it seems like we might want to take a step or two backwards and make sure you understand how to test circuits first. Improper testing nets confusing results.
All systems on a C3 Corvette are nominally 12 volts DC. Which means you have a positive 12 volt supply and a ground (negative) to make anything work. Usually anything from about 11-13 volts indicates proper voltage for operation of most things on a classic car.
Because of the fiberglass body, Vettes have more grounds (and more grounding issues) than the average car.
So, when you go to test a circuit, you have to make sure the ground lead of your circuit tester is hitting a good, reliable ground. The battery on C3's is grounded to the frame right outside the battery box, thus making the entire frame a ground plane. Any welded part of the frame will act as a ground.
(It wouldn't hurt to un-bolt your battery ground from the frame, clean the frame metal to bare metal, clean the end of the cable to bare metal, and re-attach the battery ground, to make sure your frame is grounded well.)
I always try to touch my circuit tester ground lead to a bare metal part of the frame when testing circuits, and failing that, touch something that I know is bolted and grounded to the frame. You may have to scratch thru the surface layer of whatever you are touching to get good contact.
I've also been known, when in doubt, to take a long piece of wire and extend the ground lead of my tester back to the actual battery negative post.
Some electrical components use whatever they are mounted with as their ground, and some components mounting are isolated from the ground plane, and require a ground to be fed to them via a wire.
Let's start there and verify you are testing properly and let the forum hive mind take over from there.
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2019 C3 of Year Finalist (appearance mods)
On my 1974 Corvette, the dimmer switch is on the left driver's side floor under the carpet.
On a 1979 isn't the dimmer switch inside the steering column?
If that's correct, how do you get to it to check it?
Here a a colored drawing of just the headlight circuit for your 79...
Notice the RED wire at the switch, see if you have power at the switch there.
Like I said earlier, that will be HOT all the time.
It looks like there is a dedicated black wire at the switch connector (Chassis GROUND), that would be the GREEN arrow on the drawing.
Now "IF" you have power to the switch (RED) wire pull the switch out to the second position.
Find the dimmer switch connector (On Steering Column) and check if you have power to the YELLOW wire at the dimmer connector...
Step By Step you will get this...
Last edited by bmotojoe; May 10, 2024 at 05:03 PM.
A few years back, I replaced the old incandescent bulbs in the speedo and tach. Being a bit lazy, I left the speedo and tach cables connected, but still had to Unplug the headlight plastic connector plug. Put everything back and no lights, I had not orientate the headlight connector correctly. Check to make sure the plug is oriented correctly. Also tons of posts about BAD headlight switches right out of the box. Good Luck.
I知 flying blind!!!!!
