I've only had my 72 a few months and have been fixing other things (with a lot of help from the search button on here), but now I'm trying to troubleshoot my instrument lights and parking lamps/tail lamps not working. I was suspicious of the headlight switch, especially since they all miraculously came on one night when I was fiddling with it.
Anyways they have not worked since so I tore into the dash and removed the old headlight switch, went to the local parts stores and found none of them supplied one with the vacuum ports for the pop up head lights. Where can I get one that does or do I need to frankenstein the old and new one together?
I did install the new one w/o the vac ports to check to see if the instrument lights and such would work but still nothing. No parking lights or tail lights either. What else should I be checking here?

 

Any of the Corvette vendors, such as Zip, will have the switch.

 

Yea I've seen them on all the vendors sites, but none of them seem to have the vac ports in the pics and I don't want to pay 40 bucks for the wrong 15 dollar part. Just want to make sure I'm getting the right one, every parts store i've been to has the switch w/o the ports listed as the correct one from several vendors. I'm also still unsure if the switch is even my problem?

 

The switch has to be grounded well. It's difficult to test with the switch out of the dash or the dash partially installed.

Have you checked fuses? IP and running lights are fused.

 

I had replaced all the fuses, but havnt tested them yet. (none were blown). How do I go about testing them with a multimeter? Also as far as the grounding of the switch, I'm assuming thats done with that thin piece of metal coming off where the switch threads through the dash right?

 

Bingo- its not the switch.

 

I doubt your problem is the same as mine, but I had a wire melted in my loom. New loom $750 from wilcox, lights that work PRICELESS.

 

Okay I finally have a day off to look this over, need some help because I've never trouble shot electrical problems. I am using a multi-meter because I was able to borrow one. Using the DC setting I checked for power to the red and orange wires to the head light switch. With the red lead on the red wire and black on the switch ground 12 volts. With the headlight switch pulled out and the head lights on (the headlights do work), still 12 volts. I moved to the orange wire. Red lead on the orange wire, black to the ground, 12 volts. Pull the switch and it goes to zero volts. Now am I testing this correctly? I am pretty clueless with the electrical stuff. I have a brand new switch in the car as well. The ground at the switch looks good, and I'm assuming the running lights are well grounded because my turn signals do work. Any help is greatly appreciated!

 

Remove the Taillight fuse,clean the connectors and fuse ends ,snap the fuse back in and retest

 

Roger You are BA. And I am a DA. The fuse connectors were indeed a little crusty and now the running lights work. I am assuming the inst. light fuse is probably the same culprit for those as well? I broke it trying to pry it out so I will have to get another one and try after I clean up the connectors. Thanks a bunch!!

 

Your welcome. Remember the tiny instrument fuse is only hot when the HL switch is pulled out,power comes from the dk green wire at the HL switch.

 

I went through this about 2 years ago (you can probably find the threads on it). I bought both wiring diagrams from Doc Rebuild and now use them ALL THE TIME. Best $$ I've spent on resources for the car. Once you have those and have a better understanding of the circuit you can use your voltmeter to test the circuits one at a time until you find the problem. Be advised it took me several days to get it all figured out but eventually I found a wire that had come out of the harmonica connector that was causing my problem (no dash lights). Sounds obvious when I write it but everything was so bubba'd up it was hard to find.

I used the continuity function to find it, do you know how to use that feature on the voltmeter?

Wiring diagrams:
http://docrebuild.com/oosoez.html

I like them because they show the shape of the connector and the colors of the wires.

After I figured it all out I changed everything out to blue LED's. Awesome mod I think.

-Dan

 

Yea I used the continuity test to figure out that all the wiring and switch in the headlight circuit were indeed intact. Pretty handy. The doc rebuild diagrams are in the mail actually, can't wait. I have found very little of bubba's handy work on this car to date thankfully. With the exception of every screw, bolt, and fastener seeming to be incorrect or missing.

 

I changed my lighter to a newer aux. plug for my cell phone plug. BUT now none of my lights on my dash/gauges work. I checked the fuse(7.5) and it was still good. I still changed it anyway just to be sure but nothing. The radio, aux. plug and all interior lights work but not the dash/gauges. ANY SUGGESTIONS?
Thanks in advance. 1979 C3 Vette.

 

I recently had a problem with my instrument lights not working, but in my case, it was the headlight switch.

I bought a new switch from autozone, and like you, discovered it didn't have the vacuum ports. But since it was only $10 and instant, and the cheapest one with the vacuum ports from a vendor was around $35 + shipping - I decided to modify the switch from autozone to have the vacuum ports.

All you need to do is move the metal backing plate from the old switch, to the new switch. But there are a couple of things you will need to address to do that. One is that the portion of the ceramic rheostat peice, where it fits into the metal backing piece, is larger on the new switch. So you either need to use the old ceramic piece (which is what I did, since it's not a high wear part, it should be good), or cut a little out a little of the metal, so the ceramic piece fits. The other thing, is that if you look at the sled-like piece from the old switch, you will notice a small grove in it where the tang from the vacuum ports fits in. You need to cut a similar grove in the new sled. After you do this, you can reassemble the switch (making sure the tang, goes into the grove you cut), and it should work fine.

$10's and now, is much better than >$40's and next week.

 

I've replaced my old lighter with a aux. plug for cell phone. All is working with it now. All interior lights, radio, blinkers, brake light and high beams light all work. BUT not the dash board lights do not work. I've check all the common places,fuses etc. and all is good. BUY it did notice a orange wire behind the old lighter/near stereo area have been cut. These gauges and dash lights used to work until about 10 days ago. Don't thing it's the HL switch. BUT if it is how do I replace it?