I pulled and pushed the switch pin under the dash but one headlight still stays stuck up. Any clues? could it be a bad relay? how do I fix this? This is on the 77

TIA

 

Check all the vaccumn connections that is usually the weak point of the headlight system. At least that is the system on a 70 and i believe it is the same on a 77.

 

my manual also says not to try and close it by hand if they didnt open you could just pull the hose off the back of the actuator and open it by hand but never try and close it by hand why im not sure.

 

The problem is most likely a vacuum leak, a bad actuator, or a bad acutator relay. Test the system with a vacuum gauge.

You can close the headlight manually. If it is up, it is in it's locked position. To unlock it, you will need to reach up from underneath, and gently pull the locking linkage forward. This will allow the headlight to come down.

Be careful not to pull on the headlight open switch (electrical switch) which is attached to the side of the linkage.

 

On my 78 I had the same problem, I found a hose off under the dash

 

....or open them for that matter (but that needs a prying tool )

I've had minor problems with mine (and they currently "wink" when off - open and close - which my vette mech said was just the main check valve leaking at low vacuum) and at times would have to close them manually - just because they look silly open when the car's off!

You develop a feel for it. The first couple of times I did it I used a flashlight to look at what was happening, but you get past that.

Reaching your hand through the open headlight follow the mechanism in the center down quite a ways under the headlight piece until you get to a sort of lower knee. You push the lower part of that in a little while you are lifting up on the lid of the headlight door itself slightly until that catch unlocks. Then you lower the lid slightly to past that locking position while still holding the "knee" out of locking, pull out your hand and let the headlight door close on it's own. Don't use any force on anything - it's not at all required past the little effort to overcome the small spring pressure holding the "knee" in locking position. Don't push down on the locked open headlight door of course, but the mechanisms are pretty tough, if a bit twitchy.

 

Already know how to open and close headlights manually.
I don't understand how a leaking actuator seal causes the headlight
to stay up??
What I know is a leaking actuator seal causes the headlights NOT
to pop up.

 

leak causing it to stay open - however, the vacuum system does have to work the mechanism to unlock the "knee" I was babbling about. Possibly if that was insufficient, it couldn't unlock to close.

I also had a general problem with mine with slow or non opening and such on both after a long period sitting I cured with an injudicious application of WD40 and Kroil. Mine do run faster, up and down even (yeah, not sure why), since I replaced all the vacuum lines - but now I have to change that check valve.

 

The default for C3 headlight vacuum systems is...no vacuum headlight doors open. Seems more logical for it to be the opposite, but GM designed it this way so the headlamp doors would not close driving along at night and suddenly low or no vacuum. I developed the same problem as your having a few years ago, Turned out It was the vacuum relay failing.
Its a hassle diagnosing and fixing these vacuum systems, Hope this helps.

 

i had the same issue. All i did was rub a thin layer of grease over all the moving parts. Like the grooves for the pins and the hinge and BAM. Works fine.

 

You have a leaking rod seal in that actuator. But when you replace the rod seal do both of them at the same time (the seal kits have enough parts to seal both actuators).