Searched but I couldnot find. One headlight will not go down I push on it but it seems stuck. How do you release it to make it shut? 1978 Vette

 

reach up from underneath and toggle the linkage. then you can slowly push it the rest of the way down.

 

Thanks I will do that this evening.

 

Thanks I will do that this evening.

 

Underneath you will see a big spring mechanism right in the middle. Pull down on this and it unlocks the headlight. That was my routine every morning before I finally fixed my headlight vacuum system this week.

 

Mine just started doing this too. Doesn't come down all the way on the right side. So I give it a firm push and it kind of snaps into place. Is this a fittment/alignment issue or a vaccum problem?
-CR

 

Do not just push from the top - you can actually end up doing more damage to your system - the best and only way you should do that is lay on your back -- look up under the nose and break the vacuum by pulling down on the bar that the head light elevation adjustment screw is attached to in the middle of all those springs. If it was a fitment adjustment problem you'd know by all the scratches and paint chipping around your bucket openings. Sounds to me you have a vacuum problem starting. The normal culprits: regulators, actuators and vacuum lines.

 

If the headlight warning lamp stays on when the lights appear to be all the way up, should I be concerned? Is this an indicator of future problems that might arise or just a stuck part somewhere? I know there is a linkage that might be sticking, but it looks like the headlight is all the way up to me.

 

I also have the headlight alarm light when my lights are fully up. You can easily located a small microswitch on the headlight mechanism. The switch has a small black button and an electrical plug connected to it. If I remember-- the switch button gets pushed in when the headlight is fully open. I found that one of my switches was missing/broken off, and the other's button was stuck pushed in. I ordered two of them from Corvette Central and am waiting for shipment. I want to get this fixed before I burn out that alarm light bulb!

Speaking of alignment-- I can see my passenger side headlight rubs on one side against a chrome piece near the nose. I think it's part of the grill support. If I can't adjust the headlight a touch I might try to grind down that metal a little.

 

Look in the shop manual for "headlight bucket "IN/OUT" adjustment. I think yours is easier than my 81 for adjustments.

 

I have the assembly and shop manuals-- thanks for the tip. I didn't realize the alignment could be adjusted to the left and right.

 

Thanks for the tip, I'll check it out.

 

I have a similar problem. The driver side one only comes up about an inch on its own. If you put a couple of ounces of pressure under it, it will open the rest of the way and latch open. Both close fine.

I assumed it was a leak in the opening hose on that side, but it sounds like it could be more complicated than that. Any suggestions for me?

 

First of all-- make sure one of the large vacuum hoses didn't fall off between your headlight actuator relay and the actual headlight actuator. Then manually operate the headlight up and down by hand to eliminate any mechanical binding or rubbing issues.

Now do you have a vacuum pump? Very simple to test. Just find the headlight actuator (the gold device that actually lifts the headlight up and down) and disconnect both hoses. One connector will raise the headlight when you pull vacuum, the other will close it. Use your vacuum pump to connect to both sides (one at a time) and test the operation of the headlight up and down. After you have fully opened or closed the headlight by pulling vacuum, the actuator should then hold at least 30 in-Hg vacuum and not leak with the other connector open to atmosphere. You can easily see a leak on your vacuum pump's gauge. If you test the actuator both ways and it goes up and down without leaking-- your actuator is not the problem. Reconnect the two hoses.

Now find the associated actuator relay (has 4 hoses on it). Some cars have two relays-- one for each headlight. Mine had just one to control both headlights. Not sure if it's the stock setup, but seems to work fine-- the actuators are just connected in parallel from the relay.

Disconnect the top small hose (typically with a white stripe) and connect your vaucuum pump. Does it hold vacuum at 30 in-Hg? if not, the relay diaphragm is leaking and replace the relay. If so-- let's test the operating side of the relay. Connect your vacuum pump to the middle of the three larger connectors-- usually this is the yellow striped hose. Connect a vacuum gauge to the bottom large connector and pull vacuum. you should see the vacuum gauge follow your pump and it should hold vacuum. If not-- your vacuum operating side of the relay is leaking-- replace it.

If everything seems ok-- reconnect all the hoses except for that small one on top of the relay. Reconnect your vacuum pump to this connection. Start the car to supply the operating vacuum. Use your vacuum pump to open and close the headlight. Obviously the engine is running so have a long enough hose so that you are safely away from all moving parts! If it operates ok-- you know that your operating system is ok-- you are just not getting the proper vacuum (or loss of vacuum) to the relay's control vacuum connection. Verify this by connecting a vacuum gauge to that white hose and measure the vacuum when you operate the headlight switch (or manual override). Keep working back in the control circuit until you find the problem.

If the headlight doesn't operate-- you probably don't have enough vacuum in your operating system-- possibly another leaky actuator, a bad hose, etc. Connect a vacuum gauge to the actuator hoses to see the vacuum as it is applied and removed from the actuator when you operate the pump. Also on my car the heater vacuum system taps off of the operating vacuum-- so that can be a culprit as well.

I am writing this here at work from memory and from my basic understanding of the vacuum system after studying a hose routing diagram in bed one night this week and then going out the next night to see if I can test it.

 

Could be a bad relay on that side - if you have some extra hose and a couple of hose tee's you can run both lights off the same relay and see if that corrects the problem. Otherwise you may have a leak in the vacuum hose on that side. YOU WILL have to trouble shoot - so set aside several hours of work. Look around on here for the vacuum hose diagram - double check it against your particular model year - but I don't think this setup changed that much over the 14 year run. This has got to be the most complex type system just to open F###king lights designed. Two electric motors would have been so much less complicated.
Hopefully most of you are pre-1981 - the shop manual lies for placement of a lot of things up under the nose of the 1981. Position of the horns for one thing - they are burried in the fenders, NOT IN THE NOSE and the information on the headlights is totally wrong!

 

What amazed me was how many vacuum leaks I had (a few pretty bad ones) and that the car seemed to idle very smooth. I think the stock cam produces so much vacuum it can compensate for a lot of leaks.

Amazing how much faster those headlights operate now that I've plugged up most of the leaks!