Hi, I have a c3 79 project vette and I am dealing with a problem with the courtesy dome light. Basically, the light stays OFF when I open the door and it turns ON when close it. I attach a video link of what happens when I tight/lose the screw that holds the frame (all car doors closed).
Basically when I loose the screw light goes OFF, when I tight it it goes on.

link:
I changed the courtesy timer circuit but NOTHING happens. Problem persists.
Does anyone know what's wrong with this wiring? what type of problem I am facing?
Thank you
Siol

 

The video shows the light going off when you tighten and on when you loosen.

 

yes, that's the point to show that there is something wrong.
With the door closed, the light should go OFF, not ON. This light stays ON when the door is closed.
Also, the light should be ON regardless of tightening, right?
Thank you
s.

 

<<your words.

On your video when you tighten, it goes OFF, not on. Your video shows the exact opposite of what you wrote.

 

Sorry, I meant the opposite.
Anyway, when the door gets closed the light stays ON. ON forever. with all doors closed. The light stays ON with all doors closed.

Do you have any idea whats wrong?
Thank you
S.

 

Is the screw tight?

 

Yes. But when tighted it light never turns ON.
But if I let it loose, the light stays ON forever when all doors are closed. Then goes off when I open the door.
s.

 

same for both doors?

 

yes

 

Ignition turned to off and headlight switch turned so overhead light isn't activated?

 

Yes. Thats correct.
s.

 

Has it been like that since you've owned the vehicle, or did you change something recently that appears to have caused it?

The courtesy light switches in the door frame should open the circuit when depressed (door closed). For your light to come on when both doors are closed, at least one of your door switches must be closing a circuit when depressed. This assumes no funny additional things in the circuit. I'm not sure if the "timer circuit" you mentioned would affect this basic function.

If it's just the basic circuit, then I'd say one of your door switches are faulty, or was replaced with one that is working opposite from what you need, but I can't figure out how that would have happened - I'd assume all door switches are designed to open the circuit when depressed.

Inside a momentary switch is just two exposed leads and a plate that connects them. If the switch is default "off", then the plate is held above the leads with a spring until you push them together. If the switch is default "on" (like in a car door), then the spring is holding the leads and the plate together until you push them apart. If, in your switch, the internals got loose, I guess it's possible the switch started functioning the opposite way. I've gotten a switch to do that on purpose before, but I had to crack it open to modify it.

 

it has been since I owned it. I changed the timer circuit and made NO difference. so that's not the problem.

the door switches work because when I open the door, the passenger lights go ON...it's just the courtesy light that does it inverted and never stops...

I still don't understand what I have to check to fix it...
s.

 

It takes 12v on one side of the bulb, and ground on the other side to light the bulb. 12v should always be on one side and ground should be supplied on the other side only when the door is open or the headlight switch is rotated to turn it on. Find out where you're getting a ground when you turn the screw and you'll find why the light is coming on.

 

I usually find that anytime you have a weird electrical problem that it is usually a ground issue.

 

You have a short to ground in the lamp housing.

Why am I confident to say that?

Because no matter which way you turn one of the screws that retains the housing it should NOT light!

Completely remove the lamp housing. Pinch the lamp connectors and you can push them through the back side of the housing. The positive (orange wire) connector should have +12V at all times. The negative (white wire) connector should have -12V ONLY when one or both of the doors are open. If the white wire has -12V at all times, start removing trim panels until you find where it is contacting ground.

I'd say there's a good chance that the white wire broke somewhere near the lamp housing and that someone connected it to a "good ground" not knowing that the lamp is turned on by supplying ground--not power!

 

thank you so much SwampeastMike. It sounds like you got it...I can feel it. This is a project corvette and going through it I found somebody has really really messed up thing...seems like they just did stuff without knowing wtf they were doing...
I will do as you say...might take a while finding it...

which trim panels u mean? the one on the t-top?
Thank you
siol...