Ok guys, I know there are a bunch of subjects that get beat into the ground, but either A) I don't know how to use the search to get ONLY C3 results, or B) nothing is specific enough for my problem. So, here we go.

Recently, I started having trouble with my dash. It started one day with the headlights not going down when I turned them off, and I thought 'no problem, probly just a vacuum leak.' I had fixed that plenty of times. But, it's not the vacuum separater up by the firewall this time. Then, I noticed that my dash lights weren't coming on with the headlights anymore. No idea what would cause that, cuz I checked the fuses, and they all looked fine to me. Now, my speedo is starting to "bounce". It's never done anything like that before. This car is going to drive me nuts until I do a full resto on it.

So I guess my question is, what would cause the dash lights to not come on and the headlights themselves to not go down? Should I trace vacuum lines or would it be electrical? And is there something common that would cause all three of these things to happen at once? Or is it 3 different, separate problems?

This is my daily driver, and I haven't had a lot of time to just mess around with it. It wasn't affecting driveability, so I haven't been too worried about fixing it lately. But I just got put on night shift, so driving without knowing how fast I'm going gets old. I have to follow traffic to make sure I'm not speeding.

 

Hi, I'm not sure if all three are related with one common cause. But I know that I had issues a long time ago with my headlights on my '80 not going down. There is a vacuum connector behind the carburetor on the intake manifold. On mine, the vacuum hose that was part of the headlights was disconnected. It was there lying next to the connector just not hooked up. Hope that helps you out with the headlights. As for the dash lights, mine developed the same problem. I have no dash lights. My dash lights started flickering whenever I would touch the deadlight switch to turn them on. They would flicker even more when I would turn the **** to adjust the brightness. This went on for a while until one day they just never lit up again. I'm going to replace the headlight altogether. Hopefully that will fix my problem. I remember reading somewhere that I bad headlight switch could cause a fire! Look into it and hopefully you'll find some info to help you out further. This club is awesome and I'm sure you will get other recommendations.

 

it sounds like you have a bad headlight switch .the speedo is a differant problem .it needs lubed.

 

More than likely your headlight problem is in the light switch. Also check the override valve.

 

What's an override valve?

 

the valve under the sterring wheel column

 

The override valve is under the dash,just below the steering column.It's a push/pull switch. Go to this site http://www.corvettemagazine.com/2002...acuum/vac1.asp Or this one http://www.corvettemagazine.com/body...both-open.html

 

first check that your dashlights are turned on, the lights switch is also a rheostat and you can turn off the dash lights, or dim them, independant of the headlights - turn on your headlights and then twist the headlight **** - see if the dash lights come on.

Also on the corvette there is a vaccum switch on the back of the headlight switch, this can go bad and cause headlights to remain in the up position.

The speedo cable in all likelyhood just needs a little lubrication, ive never had to do this myself, but i presume someone else can reccomend products and methods for this.

 

 

Ok, so I'll go to the parts store and get a new headlight switch, and I'll take apart the speedo cable and lube it up. What should I use on the cable? And how hard is it to take apart the dash to get to everything? I've never gone that far into this car before, so I don't even know where the screws are to start with.

 

I think you can reach the cable and disconnect it from under the dash, without removing it. There is a special speedo cable lube you should use and only on the bottom 2/3, leave the top 1/3 non lubed, it lubes itself through its spinning (Too much can clog the workings of the speedo). I think it is a graphite based lubricant.

Will

 

i would lube the dash cable last .most of the time the cable from the trans to the cruse control is the one that needs lubed.

 

Haha yeah, I forgot we were dealing with a '78, My '74 doesnt have CC so I didnt think about that.

Will

 

Ok, well, one problem out of three has been fixed. There was a black rod thing right under the steering wheel that looked like it was "sticking out" to me so I pushed it back up, and wouldn't you know, the headlights went right down as soon as I did. So that's one thing solved. Whatever that thing was, it wasn't seated right. I'm assuming it had something to do with vacuum from the headlight switch.

Now, I have to figure out why I have no dash lights, and the speedo cable.