My headlights are stuck in the up position and will not go back down. They seemed to be locked this way, is there any way to get them back down again mechanically until I can start trouble shooting the vaccum system. Has anyone else had this problem, most people I talk to have the exact opposite problem of them not coming up.
I'm not certain if the 77 is the same as my 78, but...
Check under your steering column at the bottom of the panel for a little black knob that is pulled straight down towards the floorboard.
When that knob is pulled out, my headlights will stay up. With the knob pushed in, my headlights will go down when I turn the headlights off.
Heidi
Hello C3forme,
The default position for a C3 headlamp vacuum failure is open. Ive been down this road as have many . I started by just replacing the hoses and the control valve. For me, the control valve was the main culprit. Its function is to regulate vacuum to the actuator and other headlamp,wiper and heater controls. I have only one control valve for the headlamps on my 69. Later models had one for each headlamp actuator. Replacing my leaking one solved the problem, But still I dont rely on my vacuum system to be leakproof. I plug it except when I want to raise the headlamps, to ensure that my motor runs optimal. Just my choice, its probably not even a problem. My priority is the vacuum to the distributor advance.
There are schematics of the c3 vacuum system, but I dont have the links offhand. I think Zips has a schematic with components.Also, to replace the whole c3 vacuum system, would be a daunting task, in my opinion, especially the components behind the dash.
Hope this helps..
Tom
Hello C3forme, If you can reach under your front dam, you can pull the arm down on the system. This will unlock it. Then they will go down, it is the arm between the two springs. Be sure you pull straight down. I had an 80 like that. if you can't figure it out call me. send me a PM and i'll give you the #. Good luck
There are two relays. They have 3 ports on them. One thin, and two thick.
The thin hoses routes to the inside of the car. This is the control line. When you turn on the headlights or pull down the override there is NO vaccumm on this line. No vac. means the headlights should be up.
You problem could be in this line, or the switches.
The other two ports on the relays are for either side of the actuators. One side makes the lights go up.... the other down.
The problem is old parts and hoses will leak a little. This makes the system work poorly which is much harder to fix than if it were dead altogether!
ZIP sells a little booklet on this stuff for $9. Its overpriced for about 10 sheets of paper, but very useful still. It is worth the $$ as it will save your hours of guessing.
I'm not certain if the 77 is the same as my 78, but...
Check under your steering column at the bottom of the panel for a little black knob that is pulled straight down towards the floorboard.
When that knob is pulled out, my headlights will stay up. With the knob pushed in, my headlights will go down when I turn the headlights off.
Heidi
Thanks Heidi. Yep, I know about the knob under the dash. I know how the system works, I just don't want start replacing things that aren't broken. I thought maybe I could get a few ideas of the most common problem that people find to be the culprit and look there first. I know Zip has a diagram for the vaccum system, but it is for older models where the vaccum tank is behind the left fender well and has a wiper door system also. My car, and most likely yours, has a long vaccum tank up in front up the car just front of the radiator and a emission behind the left fender well. The hose routing on the older ones appear to be different also, because of the wiper door system. I haven't been able to find the correct diagram for this year car anywhere yet. I even bought the service manual for the car thinking it would have it in there for sure and how to diagnose the system but it doesn't, it has everything you want to know about the car in there except that.
If you are going to play with the vacuum you need to buy a vacuum gauge. Costs about $10 - 15 from NAPA if I recall correctly.
An easy thing to check is the vacuum to the override. I start here because I know the circuit back to the carb but you can start anywhere and work your way to the point that the vacuum fails. Pull the hose off the override that comes from the light switch. Plug in your vacuum gauge. Play with your headlight switch and see if you have vacuum there. If you do head toward the headlights.
If not, then go to the engine and find the vacuum line that goes into the car. It comes out behind the carb and heads toward the firewall behind the gauges. It has a check valve and a filter. Pull the vacuum hose off these items and check them one at a time until you find where your problem is. If you end up with vacuum going into the switch but not to the override you are going to have to get behind the driver's side dash panel by removing the dash pad.
I'm not certain if the 77 is the same as my 78, but...
Check under your steering column at the bottom of the panel for a little black knob that is pulled straight down towards the floorboard.
When that knob is pulled out, my headlights will stay up. With the knob pushed in, my headlights will go down when I turn the headlights off.
Heidi
I was blindly trying to find my fusebox under the dash and pulled that knob down on my 1980. Couldn't figure out why the headlight popped up by themselves. Then they wouldn't close. Thanks for the help!
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