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How should headlights work?

wrc3

Well-known member
Joined
Mar 18, 2002
Messages
228
Location
Arlington, VA
Corvette
1976 L-48
Ok I have replaced almost the entire headlight vacuum system. Hoses were shot and I am now getting good vaccuum 19-20 all the way down to the acutators, which are brand new. When my lights open they both hesitate then the passenger side opens fairly quickly and then after it is up all the way up the drivers side opens quickly. Is this the way it should work? Or does this mean the relays are shot too?

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sac001

Guest
I'm no expert on the headlight system, but either there is a vacuum leak (doubful, but possible even with new hoses) or one of the valves in the vacuum system might be bad, or even in backwards. (I don't know if they're called relays or valves but I think we're talking about the same thing.

I believe nut posted earlier that you really need the assembly manual for this project. They have decent vacuum diagrams that would help you with this one.

Good luck and welcome to the CAC!

Steve :W
 

cscarlson

Well-known member
Joined
Jan 27, 2002
Messages
876
Location
SYRACUSE ,UTAH
Corvette
2003 50Th Corvette
check your vaccum canister, it is under the front just behind the headlights, it looks like a coffee can, it could have small holes in it which can allow vacuum leaks.
 
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vmrod

Guest
I could be wrong, but it sounds more like the vacuum relay and not the actuator or vacuum canister. If your headlights are quick to pop-up it sounds like the proper vacuum is there for operation.
It sounds like the controlling vacuum that is causing the problem. The tiny hose on the vacuum relays are the control line. (If disconnected the headlights should open up.) Retrace the tiny hose and see if it is OK. Mine was squashed inside the hose holder on the fender, and prevented the vacuum from operating.
The control vacuum line originates from a "T" fitting near your brake booster. It goes into the driving compartment and to your headlight switch. It then goes to your headlight override switch (under dash between speedo gauge and tach). After that, it goes to the vacuum relays at the front of the car.
Check it out and see if those hoses are still OK. (not squished). I can post a diagram, but I have to draw it up first.
-Vic
 

wrc3

Well-known member
Joined
Mar 18, 2002
Messages
228
Location
Arlington, VA
Corvette
1976 L-48
Ya I am getting good pressure to the relays, but I guess I need to test after that to see where the problem lies. I have one of those gauge tester things so I will just start pluggin it around on hoses until it drops off.

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