Well I got a vacuum gauge and tested the switches, which I believed to be my problem..turns out I was wrong. Both switched will hold a vacuum, so I disconnected both ports that go into the motor, one goes to the reserve tank, and the other goes into the firewall and to the....switch. I plugged the one going to the resivior and pumped up the one going to the switch, it held a vacuum. I pumped the one going to the resiviour and blocked the one going to the switches...it held a vacuum. When I opporated the switches with them at vacuum, I lost some vacuum but not to much, plus I hear NO hissing noise. However, when the car is running, and I try to get my lights to go down, I get a hissing at my switch. I went under the front end and I can lower the drivers side light manually, but the passangers side light appears to be seized...or something. Now i know that that is why my passangers side lights won't go down, but even if that side was totally messed up, wouldn't my drivers side still go down? My whole system will hold a vacuum, but when I start the car and pull the switch, I get nothing, when ipush the switch I get a hissing at my switch...What on earth is the deal? :mad stupid vacuum systems :mad Maybe I'll buy those solid mount lights...lol

Daniel

 

Did u take apart your dash and fool around with the switch? When mine did that i took off some of the dash, replaced my light switch, no problem since then...only thing...its a pain in the **** to take off and put on the drivers side dash in my opinion....so be warned good luck

 

ya I got the dash off and the switch out, I took it out of the car to test to see if it would hold a vacuum....it did..but when I put it in the car it hisses like a cat. I think I will replace it, then it that doesn't work I'll replace the override switch, and if that doesn't work I'll reseal the actuators, and so on and so on until I either have worknig headlights, or a whole new headlight vacuum system...either way the PITA's should be working by the time I am done...

Daniel

 

Dan,

I'm in the same pickle your in, haven't even started to find where my problem is, although I do hear something hissing under the dash. The headlights come up (takes awhile), but they don't come down.

Keith

 

Ya, I wish someone would explain to me how the things work. If I had an in depth description as to what happens when I pull on each switch, I would be able to troubleshoot my problem by being able to eliminate, or bypass, certain areas, then I could determine what it is. One thing I did do was to hook my vacuum pump directly to the headlights, after about 20 seconds of pumping each side started to go down. However when I put my pump on the other port, and pluged the opposite side, the lights wouldn't come back up...I don't know what that means, but.....

I need someone who's done this before watching over me...lol

Daniel

 

"If I had an in depth description as to what happens when I pull on each switch, ..."

You may want to pick up "Troubleshooting the 1698-1982 Corvette Headlight and Wiper Door Vacuum Systems" by Frank C. Prow II. I think you can get it from most of the catalogs for about $5.

 

I think I know what my next purchase is gonna be.... My gawd, and it's less then $10... :hat

 

Daniel;

Log on to : http://www.members.home.net/awsvette/vacuum.htm
and print it out. It describes every part of the system in detail and tells you step by step how to troubleshoot it. No charge. I think you already have all the tools you need to do it. Just take some time and apply a little patience and I think it'll do the trick. It's very satisfying to fix something like that.

 

I have done all those tests in the past, and everything checks out...??? The one thing that doesn't is on the headlamp actuator, when the headlights are closed, and I connect my vacuum pump to the green line and my lights do not open, and no vacuum is formed. It says my internal diaphram is leaking, however when the lights are open, and I attach my vacuum to the red line, my lights close, and it holds a vacuum, which it says that my internal diaphram is in good condition. So its contradictory(if thats even a word)...my conclusion is, my actuator seals are bad...which would indicate the lack of vacuum with attached to the green lines. does this make since? If that is the case, it still doesn't explain the hissing noise in my switch...perhaps I have a clogged line? a little info, when I was testing my lines, I noticed that where it y's off(coming out of the manifold, it goes to the check valve and y's off there)...well the line that goes to the reserve canister was completely blocked. Just past where it connect to the check valve, I felt what felt like a pensil in there, when I cut that section out, I found a little rubber peice that almost looks like a vacuum line block...like something manufactured. Its a little rubber peice and it fits VERY snug into the line...in fact I had the cut that section of the line long way to open it up to get out the clugged peice(I was close enough to the check valve that I could attach the line to it without an adapter and more line). Was this supposed to be there? I doubt it...but it makes me wonder...how many more of these little things will I find in the rest of my system...? Maybe thats where the hissing is coming from...maybe my lines are blocked off and the front of the car never gets any vacuum, and when I push the switch the hissing is the release of pressure do to the lack of "room".....
:confused: :confused: :confused:
I doubt that makes any sence...I just got done with homework(3 hours worth of math homework...YUCK). :rolleyes: If it is confusing...just dissreguard it.

Daniel

 

The hissing sounds like (no pun intended) a vacuum hoses is off at the light switch. The lights go down when there is vacuum on the little hose at the headlight vacuum control valves. When the headlight switch is off, vacuum is piped straight through the light switch. When you pull the light switch on, it should block the vacuum supply line (which is shared with the wiper door) and vent the little line going to the vacuum control valve. Since the vacuum supply is blocked when the switch is pulled out, no hissing, but push in the light switch you pipe vacuum to the port with the missing/bad hose.

You can get at the light switch fairly easy, considering you'll have to slide the dash pad forward to reach it. You might try, but I don't think you can reach it from underneath. Be sure to drop the stering colum before you slide the dash pad forward. Beware there are three bolts holding the column, one is hiding in the back and is easy to miss. Get all the screws out of the dash pad (two in the door jam, three in the top and two in the gage bezel... I think), try not to pull it forward more than necessary because if you pop out an instrument lamp, it is a real PITA to get them back in. There are two vacuum ports on the light switch that are 90 degrees clockwise from the electrical connedtion. If the light switch is bad, to remove the pull ****, pull it to the full ON position then you'll find a little button just behind the vacuum ports, (PITA). Push this release button and you should be able to gentley pull the **** the rest of the way out. From here getting the switch out is pretty straight forward.

 

daniel77350,

Sorry about the color coding problem with the vacuum hoses. When I updated my web site, I mixed the colors up. I corrected it. Here is a generic picture of how the actuator works from the inside.

 

I have learned while redoing my system is that if you have the lines on your switch backwards, you will get the hissing sound your are talking about. Even a new switch does it. Not sure why but try reversing the lines on the switch and see if it stops hissing. lou

 

if the hoses are backwards the hissing is constant, if they are correct the hissing only lasts a second or two. I have had my switch out of the car about 5 or 6 times...Im half tempted to replace all the hoses, plus the seals on the actuator...

Daniel