Help Troubleshooter Headlight problem
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Racer
Joined: Nov 2009
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From: Suffolk Virginia
Help Troubleshooter Headlight problem
Hey Guys,
Ever since I bought my Vette the headlights come up slowly, right then left. It's never bothered me enough to look into it, but now the left light only comes up halfway. The P.O. did some work in there, the left actuator looks new.
Anyone have a guess what to check/replace first? Any good was to test parts?
Thanks! - Jay
Ever since I bought my Vette the headlights come up slowly, right then left. It's never bothered me enough to look into it, but now the left light only comes up halfway. The P.O. did some work in there, the left actuator looks new.
Anyone have a guess what to check/replace first? Any good was to test parts?
Thanks! - Jay
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from what I remember with my C3 my headlights never came up together per se...but I would venture to guess its a vacuum issue.
I will now step out and let someone with waaaaaaaaay more C3 knowledge respond.
Good luck
I will now step out and let someone with waaaaaaaaay more C3 knowledge respond.
Good luck
Former Vendor
Joined: Aug 2006
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From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
My best guess is that the issue is the relay, but it could also be a hose pulled lose or one cracked. Check all the hoses first.
You have to have everything correct at Point L for the right side to work so the issue is from this point forward...
If you want to see if the problem is the relay... Use the yellow hose to test the actuator. You can use the vacuum off this hose to pull up or to pull down.
Another way to tell is to switch all the hoses from one side to the other. If the problem travels to the other side then you have a defective relay.
Report back..
Willcox
You have to have everything correct at Point L for the right side to work so the issue is from this point forward...
If you want to see if the problem is the relay... Use the yellow hose to test the actuator. You can use the vacuum off this hose to pull up or to pull down.
Another way to tell is to switch all the hoses from one side to the other. If the problem travels to the other side then you have a defective relay.
Report back..
Willcox
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Joined: Sep 2002
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From: Myrtle Beach SC
Ever since I bought my Vette the headlights come up slowly, right then left. It's never bothered me enough to look into it, but now the left light only comes up halfway. The P.O. did some work in there, the left actuator looks new.
Anyone have a guess what to check/replace first? Any good way to test parts?
Anyone have a guess what to check/replace first? Any good way to test parts?
We've had an extensive discussion on the topic over the past year and I've included the link below. A Pace Car guy did a very nice job of putting together a set of schematics along with narrative that will give you a system's perspective of your vacuum operated highlight system. He also references both the Wilcox diagram but also provides links to individual component troubleshooting tests.
I'm going through all this as well with my 78, starting with system tests and narrowing it down to the relays and actuators. It takes a few specialized tools, patience and the instructions published in the thread referenced. I add a six pack to facilitate the patience piece. I might add that my 78 vacuum degraded not unlike what you've described. Now...very little works. My testing showed that of the four component individual tests, two failed completely to hold vacuum while the passenger side would hold than vacuum would leak down. I'll replace relays and have the actuators rebuilt.
How Your Headlight Vacuum System Works
Keep us posted on your progress
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Melting Slicks
Joined: Apr 2007
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From: Tolland CT
Sounds like a vacuum issue to me. I had a similar problem with my 70. Turned out to be the vacuum relays were leaking like sieves. All three were leaking on mine, wiper door and both headlights. Headlights pop up quickly now, together....
I'd start looking for a bad hose or some other leak. If that's not it, the relays would be my next guess. Do you have access to a vacuum pump? I used a hand held unit, used for bleeding brakes, to test the vacuum relays.
I'd start looking for a bad hose or some other leak. If that's not it, the relays would be my next guess. Do you have access to a vacuum pump? I used a hand held unit, used for bleeding brakes, to test the vacuum relays.
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Joined: Mar 2004
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From: Ojai CA
Hey Psycho, I agree with Speedreed8, I had exactly the same problem with my 72'. I found lots of info on the forum but never could figure the real issue. I then found an if/then guide that starts at the manifold vacuum source and goes step by step to locate the issue. This is something that a person with very little mechanical experience can fix themselves with easy to find parts. First, take the red hose off of one of the actuators and put a vacuum pump on it to see if it's holding vacuum. Then do the same to the other. If they're not holding vacuum then:
Go to: http://www.corvettemagazine.com/body...both-open.html
Go to: http://www.corvettemagazine.com/body...both-open.html
Last edited by dlux72; Jun 7, 2012 at 10:47 AM.
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If one headlight pops up and you only have one relay then the relay is good.
Test the actuators you might just need a seal.
http://www.corvette-101.com/vacuum.htm#actuator
Test the actuators you might just need a seal.
http://www.corvette-101.com/vacuum.htm#actuator
Race Director
Joined: May 2006
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From: Dayton, Ohio
If one headlight pops up and you only have one relay then the relay is good.
Test the actuators you might just need a seal.
http://www.corvette-101.com/vacuum.htm#actuator
Test the actuators you might just need a seal.
http://www.corvette-101.com/vacuum.htm#actuator
speedreed8 and dlux72 called it.
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Former Vendor
Joined: Aug 2006
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From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
Are you sure of this... If you only have one relay then you've eliminated the relay as the problem by stating that one side comes up fine. If both lamps are being controlled by one relay and that relay is bad, then both fail to come up.
(You can control both with one like the earlier cars did)
After you make sure all your hoses are hooked up properly... use either the yellow hose off the relay or the large black one that is feeding the reserve tank off.. and function test the actuator.
Willcox
(You can control both with one like the earlier cars did)
After you make sure all your hoses are hooked up properly... use either the yellow hose off the relay or the large black one that is feeding the reserve tank off.. and function test the actuator.
Willcox