Help! Can anyone tell me what to do to get the headlights on my 74 Vette to work properly???? They are stuck in the on position. Don't know if it is the vaccuum hose, the switch (don't know if it is the one in the dash or possibly on the line) or something else. What parts need replacing? Is this easily doable? Thanx

 

This link will help you troubleshoot your problem, just click on "vacuum trouble" when you get there

http://www.corvette-101.com/

 

yes yes i need help too i just got my first vette and the head lights are stuck open/up, where can i find some diagrams or trouble shooting info? i have a cruddy manuel from autozoo not verry descriptive.,

 

This is a good site to check out your headlight problems. http://corvette-101.com/ click on "vacuum trouble". One thing you might check if you haven't already......there is an override swtich or "pull down" switch hanging down from the dash just above your left knee. That needs to be in the up position or the lights will always stay up. The 101 site shows this pull down switch.
Hope this helps.

 

You can make sure that there's no mechanical issues by reaching up and pulling the linkage so the lights drop back into their closed position. There's an adjustment screw to change how far up the lights go - if they're too close to "overcenter" they can almost lock open.

If they've been working okay you probably do have a vacuum issue though.

good luck

 

its not the cans that push the lights, up sounds like the vac relay in the center of the car. try taking the vac lines off the relay and push down on the H/L if it goes down make sure the line is clear and reconnect. start car put on the lights and then turn lights off (keep car running) if they stay up turn car off and push down (not hard) if they don't go down repeat take off vac line & push down. if they go down I would replace the relays or start w/new vac lines G/L

 

i disagree, it is the "cans" actual part name, headlamp actuator, that actually has a diaphram in it to push the headlight bucket up and bring it back down. unfortunately there are loads of parts in the vacuum system that can cause the lights not to work. the sugggestion about the headlight over ride switch under the steering column is a good one as the lights will remain open if the over ride is active.

if that isn't the case, you can reach under the headlights and pull the buckets down manually (do it with the engine NOT running). once they are down, you can see if they might work going up again. if they do, you at least are getting vacuum from the manifold through the check valve and filter, throught the headlight switch and over ride switch and through the vacuum relay(s). if you have a vette with a windshield wiper "door" that is vacuum activated, you will have one relay at the wipers and one relay mounted between the headlamps under the nose section infront of the hood opening. if you have a "fixed" hood and regular wipers, you will have 2 vacuum relays both mounted under the nose, 1 each for each side of the headlamps.

the most common problems is that the seals in the actuators ("cans") start to leak. that will bring the entire system to it's knees. they can be inspected by removing the grills and pulling back the dust boot on the actuator arm that is connected to the headlight mechanism to expose the seals. if necessary, they can be changed without removing the actuator from the car, you simply need to disconnect the rod end clevis and you can get to the seals. with the hood open and the engin running, have someone ativate the headlight system (pull the headlight switch on) and see if you can't hear anything "hissing". if you can try to find it because that is more than likely a source of you problem. your car is 71 and newer, so you have a log type vacuum tank behind the radiator on the frame. they tend to be a bit more durable and unless damage by accident, rarely fail on their own (unlike the earlier version mounted inside the driver's side fender.

just a suggestion, but a complete kit to replace the vacuum hoses in the system can be had from doc rebuild for around $50.00 including s detailed diagram of the hose system. you can physically check the check valve by attempting to blow backwards through it. if you can, it is bad and is letting vacuum leack backwards through the system. fortunately, all the parts ou might need are readily available.

i hope that helps you out some and provides some direction.

 

Thank you all for your prompt reply to my plea. The info was useful and understandable. Looking forward to getting the problem resolved. Really glad Corvette Forum was recommended!