75 roadster headlights

[Ross F.]

This must be the most frequent problem on C3 corvettes, but, here is what I'm seeing. Or not seeing.
First long drive after complete restoration, about 15 minutes into a night drive, the lights go out. Not the dash lights, nor the side marker lights, just the headlights. Frantic switch manipulation and high beam button stomping, and the lights come back on. This happens repeatedly at various intervals for the rest of the drive. Several times I just did nothing and the lights came back on without any action on my part. I did replace the switch with one I bought from paragon.
I also notice the idle speed change when the lights come up.
The lights pop up and down nicely when activated, so the vacuum leak is small, but noticable.
I have blocked both the contol vacuum line and the source vacuum line at various points downstream of the fire wall with no change.
So my guess is the leak is in the control line on the cockpit side of the fire wall. Again maybe pointing to the new switch.
Thoughts?

[Jimmy P.]

Re: 75 roadster headlights

Ross,
I had the same scary situation when I put a new switch in my 73. I did not have any of the vacuum issues you describe though. First thing first though! Since you mention you just finished a restoration, I would double check all your grounds to make sure they are ok.!! Here is what I found out about the switch. There is a circuit breaker in the switch that cuts out when it gets too hot as a safety measure. Some of the new switches have faulty breakers and are not manufactured up to certain specs. Many or most of the vendors get their switches from Lectric Limited. I got my faulty switch from Corvette Central who get their switches from LL. As you also know most vendors won't let you return a switch. I called LL and they told me they had some problems with some switches, but now their newer ones were made according to spec. They told me that if I returned my switch to CC, they would send it back to them to have it checked to see if it is faulty. Then I could get the refund or a replacement switch. So, I called CC and they told me the same thing. So I returned it and indeed it was faulty and my money was refunded. Do you still have your original switch? If you do and if it was only a vacuum problem where you needed to use the bypass but the lights worked. I know it's a PITA to change the switch, but put it back in and try the lights. Let them on for a while, or maybe take a ride around your neighborhood with someone in front of you to follow in case the lights go out. If they stay on, you know it's a faulty switch. That's what I did.
As far as switches, I found an OEM. Delco Remy made in the USA switch on eBay reasonably priced and installed it. My lights have been working fine ever since. (You can read about it in my discussion board thread "73 Headlights Cutting Out While Driving")
Hope this helps explain things.
Good Luck,

[Ross F.]

Re: 75 roadster headlights

Thanks Jimmy,
when yours went out was it just the headlights, or all the lights?
When mine went out the interior lights and side markers stayed on.
the shaft of the switch does get hot. It doesn't seem to matter high beam or low beam. I have the original power beam guide bulbs.
i heard somewhere the older bulb take more load. I change to modern bulbs and it still happens.
who makes a reliable headlight switch? It's such a pain to replace switches. I only want to do this once.

[Joe L.]

Re: 75 roadster headlights

Thanks Jimmy,
when yours went out was it just the headlights, or all the lights?
When mine went out the interior lights and side markers stayed on.
the shaft of the switch does get hot. It doesn't seem to matter high beam or low beam. I have the original power beam guide bulbs.
i heard somewhere the older bulb take more load. I change to modern bulbs and it still happens.
who makes a reliable headlight switch? It's such a pain to replace switches. I only want to do this once.

Ross------


I hope you have the right switch. 1968-73 Corvettes use a 7 terminal switch. 1974-77 uses an 8 terminal switch. The 8 terminal switch will work fine for 1968-73 (and, in fact, replaced the 7 terminal switch for these model years) but the 7 terminal switch will not work fine for 74-77.

To be honest, I worry about these reproduction switches. I'd look for an NOS GM #1995191.

[Jimmy P.]

Re: 75 roadster headlights

Ross,
It was only my headlights that went out. I also have the original Power Beam Guide Bulbs. The switch that was in my car when I first bought it worked the lights fine. It was the vacuum part of it that didn't work. It wasn't an original switch but it was an older repro. When I replaced it with the new repro from CC, that's when my lights started going out as stated above. If you want to try your luck again with a new one I would try Dr. Rebuild he has one that is made in the USA a GM #1995191 reissue. It cost more than the Taiwan one, but it's probably worth it.

[Ross F.]

Re: 75 roadster headlights

Thanks Jimmy,
i will consult the Doctor!