Winking headlights..help!
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Racer
Joined: Jan 2003
Posts: 280
Likes: 26
From: Kansas
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Winking headlights..help!
The left headlight on my '69 doesn't always go down when the light switch is turned off. The right headlight is very slow to go up. The entire car was recently rebuilt. The door that covers thewindshield wipers is also not going up. After having the problem last night, the left light assembly went down on its own! Help! I've got a spook in the system. 
Race Director
Joined: Sep 1999
Posts: 11,360
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From: Plano TX
Re: Winking headlights..help! (kdzdds)
Troubleshooting involves many steps, so let's start with a test to narrow it down:
Locate the vacuum splitter/valve that is connected to the intake manifold on one side and then splits into 2 hoses. One hose goes past the brake booster into the vacuum tank. The smaller hose goes through the firewall.
With the engine idling, pull the small hose off and put your thumb over the connection on the splitter/valve.
Let us know if the headlights and wiper door pop up or not.
Locate the vacuum splitter/valve that is connected to the intake manifold on one side and then splits into 2 hoses. One hose goes past the brake booster into the vacuum tank. The smaller hose goes through the firewall.
With the engine idling, pull the small hose off and put your thumb over the connection on the splitter/valve.
Let us know if the headlights and wiper door pop up or not.
Thread Starter
Racer
Joined: Jan 2003
Posts: 280
Likes: 26
From: Kansas
2022 C3 of the Year Finalist - Unmodified
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Re: Winking headlights..help! (zwede)
Ok, pulled the hose and put finger over the valve... nothing happen except the enging ran a little rough... now what..
Navigator
Joined: May 2004
Posts: 9
Likes: 0
From: Battle Ground WA
Re: Winking headlights..help! (kdzdds)
I have the same problem on my 68, which wasn't used for years. Someone suggested I spray some silicon lubricant inside the headlight actuators. That helped a lot. One still won't go down by itself, but they open much faster now and the other one closes by itself. I did this about a year ago and it hasn't caused any problems. I don't know if this is a recommended thing to do, but it definitly helped.
Melting Slicks
Joined: May 2002
Posts: 2,508
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From: Wisconsin
Re: Winking headlights..help! (kdzdds)
http://www.corvette-101.com/
Click on vacuum trouble. That's about all the help I can provide as my system seems to work pretty well.
Click on vacuum trouble. That's about all the help I can provide as my system seems to work pretty well.
Race Director
Joined: Sep 1999
Posts: 11,360
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From: Plano TX
Re: Winking headlights..help! (zwede)
Next is to isolate the bad part(s) of the system. You can start with the headlights. Pull the hose going from the vacuum tank to the wiper door and plug the fitting on the tank. If you have leaks in the wiper door circuit they are now plugged so you can concentrate on the lights.
For your headlights you have 2 vacuum relays located in the center front of the nose (68 had only one, you didn't specify year).
By taking the center grill out you have access to the relays. Unscrew them from the car but leave the hoses hooked up.
You will need a vacuum gauge now.
Disconnect the center large hose from the relay (there are 3 in a row, plus a small one at the end of the relay). With engine running measure vacuum. This is the supply hose and should have the same vacuum as the engine.
If it has vacuum, reconnect it. Pull the small hose. Light should go up.
If it doesn't, pull the hose going from the relay to the front of the actuator. Measure vauum. If you have no vacuum, the relay is bad. If you have vacuum the actuator is bad.
That's a start. Once you have this done and working we can move on to the control circuit if necessary.
For your headlights you have 2 vacuum relays located in the center front of the nose (68 had only one, you didn't specify year).
By taking the center grill out you have access to the relays. Unscrew them from the car but leave the hoses hooked up.
You will need a vacuum gauge now.
Disconnect the center large hose from the relay (there are 3 in a row, plus a small one at the end of the relay). With engine running measure vacuum. This is the supply hose and should have the same vacuum as the engine.
If it has vacuum, reconnect it. Pull the small hose. Light should go up.
If it doesn't, pull the hose going from the relay to the front of the actuator. Measure vauum. If you have no vacuum, the relay is bad. If you have vacuum the actuator is bad.
That's a start. Once you have this done and working we can move on to the control circuit if necessary.
Burning Brakes
Joined: Jun 2004
Posts: 1,012
Likes: 5
From: Granbury, TX
My headlights are acting as an airspeed indicators. They work fine at a stop but at 85 MPH, or 70 with 15 MPH headwind etc., they will pop up and stay up until I stop. I've lubed everything and the springs are all there. Should I replace with stiffer springs??
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Race Director
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From: Lenoir City Tennessee
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As long as we are troubleshooting the vaccum circuits. My headlights will pop up if I stay on the gas for a long period of time, for instance, getting on the interstate. What would be a cause of this?
Race Director
Joined: Sep 1999
Posts: 11,360
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From: Plano TX
Originally Posted by Eddie 70
As long as we are troubleshooting the vaccum circuits. My headlights will pop up if I stay on the gas for a long period of time, for instance, getting on the interstate. What would be a cause of this?
Burning Brakes
Joined: Jun 2004
Posts: 1,012
Likes: 5
From: Granbury, TX
This could be my problem too. The higher speed also means I have my foot in the throttle and less vacuum. However, my lights do seen to pop up more in a headwind.
So, does the tank have a leak or a leak in a line from manifold to tank?
So, does the tank have a leak or a leak in a line from manifold to tank?
Race Director
Joined: Sep 1999
Posts: 11,360
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From: Plano TX
Originally Posted by Clint's C3
This could be my problem too. The higher speed also means I have my foot in the throttle and less vacuum. However, my lights do seen to pop up more in a headwind.
So, does the tank have a leak or a leak in a line from manifold to tank?
So, does the tank have a leak or a leak in a line from manifold to tank?
Burning Brakes
Joined: Jun 2004
Posts: 1,012
Likes: 5
From: Granbury, TX
Ghosts in the Headlights
Really strange. My right headlight opens up at night and stays open until I start the engine and create vacuum.
I would think the “at rest� position would be down. What unseen forces are causing the light to open?
I like vacuum issues almost as much as electrical, NOT!
Looks like I’m going to have to learn. Where can I pick up a vacuum pump??
I would think the “at rest� position would be down. What unseen forces are causing the light to open?
I like vacuum issues almost as much as electrical, NOT!
Looks like I’m going to have to learn. Where can I pick up a vacuum pump??
Race Director
Joined: Sep 1999
Posts: 11,360
Likes: 382
From: Plano TX
The failure mode for the lights is actually the up-position. Makes sense from a safety point of view. Supplying vacuum via the control circuit (headlight switch) makes them go down. Cut the vacuum and they go up.
Your problem sounds like you have a problem with the vacuum relay for that light. It switches to the open position and you have enough vacuum left in the tank to pop the light up. As a test you could try swapping the relays around and see if that makes the other light do it. The relays are about $50 ea and are located in between the headlights.
As for a vacuum pump, I use one of the cheapo mity-vacs available at any autoparts store for $20 or so.
Your problem sounds like you have a problem with the vacuum relay for that light. It switches to the open position and you have enough vacuum left in the tank to pop the light up. As a test you could try swapping the relays around and see if that makes the other light do it. The relays are about $50 ea and are located in between the headlights.
As for a vacuum pump, I use one of the cheapo mity-vacs available at any autoparts store for $20 or so.
Racer
Joined: Aug 1999
Posts: 451
Likes: 2
From: Toronto On
I don't want to highjack the thread, but...
I understand, this makes sense, but then why don't the lights go up on their own overnight, or even after months in my garage? I'm guessing it's because there is no vacuum on the relay either, therefore the actuator system is closed and there is no way for the actuators to move?
If I took the hose off the actuator, should the light go up? Just wondering if I have to make an adjustment to the "closed" position, they might be closed "too much".
Originally Posted by zwede
The failure mode for the lights is actually the up-position. Makes sense from a safety point of view. Supplying vacuum via the control circuit (headlight switch) makes them go down. Cut the vacuum and they go up.
If I took the hose off the actuator, should the light go up? Just wondering if I have to make an adjustment to the "closed" position, they might be closed "too much".
Race Director
Joined: Sep 1999
Posts: 11,360
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From: Plano TX
If you cut the vacuum alltogether the lights don't move at all. There's no spring pulling the light up (or down) in case you pull the hoses off the actuator. That's why I think the problem could be the relay. Only way for the light to go up is if the relay commands it up.
