flyinrazrback

Sorry for the newbie question, but this is my first C3. Quick question about headlights. On my 72 when I pull out the headlight **** the lights come on but I have to pull a **** under the dash to get theft to open or close. Is that normal procedure? I thought they would come open by pulling the headlight **** out but have to pull the **** under the dash to get them to open or close.

Alan 71

Hi frb,
No that's not normal.
The pull down over-ride under the dash bi-passes the headlight switch and allows you to open the headlight doors without having the headlights on. (to replace a bulb for instance)
Since the headlight doors open using the over-ride it's likely that the 'system' is ok. except for the 'vacuum' function of the switch.
There are 2 hoses on the switch…. a plain black hose and a blue striped hose. They could be reversed.
Do you HEAR any hiss when you pull the switch?
Regards,
Alan

flyinrazrback

Alan, I haven't noticed a hiss. Car is pretty loud running so will listen carefully to see if I hear it. I will check the hoses to see if they are reversed. If I reverse them and have the same problem, what is the next corse of action?

Alan 71

Hi r,
The blue hose goes on the forward nipple on the switch and the black hose on the rear nipple of the switch as mounted in the dash.
If the hoses are routed correctly then I believe it can only be a problem with the vacuum portion of the switch.
This means replacement.
It would be good if someone else would pipe up with their thoughts too.
Regards,
Alan

Mashman

Just to add a possible senario, it's possible that a previous owner had to replace the lightswitch, and replaced it with one that doesn't have the vacuum portion of the switch.

If your headlight switch goes out, you can get a replacement headlight switch from any parts store, but it won't have the vacuum portion of the switch. It's possible that the lightswitch went out, and the previous owner simply installed a switch that he was able to get locally, and manually opened the headlight doors with the override whenever he need the headlights. If this was done, they probably used a connector and spliced the two vacuum lines together.

flyinrazrback

Mash, thanks! I hope it is either your suggestion or Alan's, will make it easy to fix.

flyinrazrback

Ok, still trouble shooting here. Under my dash I have this piece hanging in addition to the small **** that is the manual override. In the process of pulling the switch but so far it looks like my light switch does have the vaccum lines to it. What is this for? This switch does nothing with the engine running, etc. Tried every combination with the headlight switch and the manual **** with this one, and no luck getting the head lights to open with just the light switch being pulled out.

Alan 71

Hi f,
There should be 2 of those vacuum override switches mounted directly under the steering column….one (on the left) opens the headlight doors, and the other one (on the right) opens the wiper door.
If there are no hoses run to the headlight switch someone has been using the override to open the headlights.
It's certainly possible that there's a problem with the vacuum portion of the headlight switch, and this was the 'fix' that was chosen.
You'll need to check the vacuum operation of the switch in order to determine if you need a new switch.
In the second picture the blue hose on the left switch is headed to the forward port on the headlight switch and the black hose is headed through a grommet in the firewall to the small port on the check valve.
Regards,
Alan

flyinrazrback

If you look at the attached picture, the one labeled #1 does nothing when pushing or pulling. #2 opens and closes the headlight doors. I guess we need to pull the switch and see how it is plumbed to #2, and sounds like the #1 is for the windshield wipers (which don't work). I need to track down one of the mounting parts for these so it does not look like crap under the dash. Alan, is that mounting system a factory part?

Alan 71

Hi frb,
Yes, the bracket that holds the 2 vacuum pull-down switches and the center electrical switch (which allows the wipers to be stopped in the 'up' position) is part of every car. It's held in place in the lower center of the dash pad by the 2 screws you see at the left and right of the picture.
Normally the vacuum switch on the left controls the headlight doors, and the one on the right controls the wiper door.
Do you have anything that shows the location for ally the parts to both systems and the hose routing? Like the Assembly Instruction Manual?
Regards,
Alan

flyinrazrback

Alan, I do not. Who carries a replacement mounting console/****?

redman76

If the vacuum switch on your headlight switch isn't working, you may be able to repair. The vacuum switch is a very simple design, but easy to bend causing leaks. I had a brand new switch that would not hold vacuum, and had to take the vacuum switch apart and play with to get it hold vacuum. To get the switch out, you have to drop the steering column and pull the dash forward. There is a release button on the switch housing that will release the **** which you pull out to get to the nut on the front of the switch that holds the switch on the dash pad.

norm84

I went through the same situation. It ended up being in the switch as suggested in previous posts. The question for you is how do you intend to use the car,,,, if you're on a restoration voyage, then I would recommend getting the GM correct switch that has the vacuum connections. The hassle to change the switch with an after market one that needs a sealed vacuum is not fun... on the other hand if you are not going the restoration route then the after market ones may be a better value for you. PS.. the switches show up on that bidding website often... but the bidding makes them a little on the expensive side...... so what else is new when restoring a 40+yr old classic??

flyinrazrback

I don't care if it is an original switch or not. My car is a smorgasbord of stuff anyhow.