The headlights on my '71 Vette don't open or close via vacuum. Even the override switch under the dash doesn't
open them. I opened them manually by just pulling them up with my hands, but now I can't lower them. How do I lower them manually. They seem stuck in the open position.

Also, what's the usual cause of the vacuum switch not working? When I take a vacuum pump to the actuator the headlights open fine. So must be a leak somewhere? But where's the usual location of leaks in the headlight vacuum circuit?

Since you have determined your actuators to be in working order you have already narrowed the problem area. Between the actuators and the intake there is an actuator relay for each actuator, a filter, and a check valve – all connected together by several feet of vacuum hoses.

If you are having trouble with both headlights I would not think the actuator relays would be the problem. Does you wiper door work? Your problem may be nothing more than a vacuum leak that can be fixed by replacing a hose.

Good luck.

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Brent |IMG|http://www.goeaston.net/~bspicer/Corvette/74Vette.jpg|/IMG| 1974 Unrestored L-48 Convertible

To get them to close manualy you need to reach up inside and pull down on the cam that the actuator attaches to. They sort of lock in position when they are fully up.

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Brian - NCM Lifetime Member

73 coupe L48, Flat-top pistons, Performer RPM Heads, Crane Cam and roller rockers, Holley 650 vac sec. Performer intake,
3.55 gear BTO 200-4R trans,
Leather seats, Seatbelt Plus 3point seatbelts, Pioneer CD player
Magnaflow Exhuast System

It sounds like you have already narrowed down some things that it is not. I had a similar problem and found that one of my "door open switches" was broken. That switch is located under the headlight door (one on each side of of the car). I replaced the broken switch ($21.95 @ Corvette Central) & it now works ok. You might want to check that also.

Let us know how you make out in getting them working again.

The wiper door doesn't open either. So headlights AND wiper door are not functioning. I checked the hoses visually and they all look like their connected properly.
I do hear a hissing sound behind the dash in the area of the headlight switch. Are there vacuum lines routed to the headlight switch and the auxiliary vacuum switches under the dash that could be disconnected? But which would cause BOTH the headlights AND wiper door not to functing. The main pie shaped vacuum canister on the passenger side looks pretty new.

--Steve

Under your hood near the firewall on the driver’s side you will see a check valve with a vacuum hose entering one side and two hoses connecting to the other. The smaller of the two hoses passes through the firewall and is connected in a series to the override switch and headlight switch before going back through the firewall to the actuator relays.

Find that vacuum leak and you will be able to fix you headlights and wiper door.

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Brent |IMG|http://www.goeaston.net/~bspicer/Corvette/74Vette.jpg|/IMG| 1974 Unrestored L-48 Convertible

Thanks Brent! Now I just have to figure out how to take the drivers side part of the dash apart so I can get at the hoses. Never done it before. Do I just unscrew the dash panel and pull it toward me? Have to remove the steering wheel? Or better just to crawl under the dash and look for the vacuum hoses.

--Steve

Steve, I don’t think you will be able to get your hand far enough to reach the switch from under the dash. As I recall you can take a few screws out of the dash (side and top) and pull it away enough to get your hand inside. You don’t have to remove the steering wheel but you may have to loosen the steering column.

If I can find my schematic for the headlight vacuum system I will send you a copy. Let me know your e-mail address. Brent

|UPDATED|5/4/2004 9:23:05 AM (AZT)|/UPDATED|


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Brent |IMG|http://www.goeaston.net/~bspicer/Corvette/74Vette.jpg|/IMG| 1974 Unrestored L-48 Convertible

This diagram has been very helpful when working on the vacuum system. It not only shows where the hoses go, but the valves and switches are close to where they are located on the car.

what is the part in the upper left corner of this diagram. ?

The little valve with 3 hoses? That is the wiper park valve. When the wipers are working...and the wiper door is open, the plunger on the valve is up...which keeps the wiper door open. When you turn the wipers off, the door stays open until the right wiper blade parks and pushes the plunger back into the valve...then the wiper door closes.

found a pretty good check list for these at
http://www.jamisoncustomcorvette.com

Hope it helps

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Mike

I attached zip ties to mine so it makes them easy to pull down!

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Try this sight in Australia. it might help.
http://www.corvettesofmelbourne.com/

Ken

Go to the "News" section and then the "Tech Articles"

|UPDATED|5/7/2004 10:57:17 PM (AZT)|/UPDATED|


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1976 Corvette Stingray L-82 4 speed 1976 Olds 4-4-2 (455 Rocket) |URL|http://community.webshots.com/user/kpilidis |/URL |IMG|http://f3.grp.yahoofs.com/v1/UGmcQBumAcZUIwWjUjZVUuoD2ZCoTmNBkCB1mdnIgR0xXHjh2LfbQTFHLD6Il3qML7tG-d1p_v0EBWLMHE1DagpEz3ZmiA/%20442%27s/Corvette%20Stingray.JPG|/IMG|

That is an awesome link for C3 vacuum headlight system troubleshooting! Thanks!!!