Hi,

On my recently bought Vette the only electrical things not working are the license plate light, the dashboard illumination and the door open-closed sensing system. With the last one, all of the inside lights stay on regardless of the door sensors and I assume that's why all the interior light bulbs are removed. I tested it yesterday and all the bulb sockets are receiving constant power.

So, I took the driver's foot panel off and pulled out the wires behind it. I can see several of those unconnected and also a couple of broken ones (6). I guess someone who has worked on a Vette electric system before might be able to recognize what's going on. Please check it and tell me anything you can think of



Thanks!

 

Let's see, I'm going to go off of my car and you can see if it helps at all.

I'd check the bulb with the license plate issue.

If all the gauge lights are out, then I'd see if a gray wire is connected to the light switch.

There are two possibilities for the courtesy lights. If you turn the light switch dimming **** all the way, it gives them power all the time. You should feel it hit a groove. Other than that, your lines are crossed behind one of your door jam switches (in front of the doors). You can troubleshoot this by taking them out.

 

Thanks for the quick reply! I had real pain trying to check the license plate bulb. How the heck is one supposed to open that? It looks like the light assembly is INSIDE the frame so even if I open those two screws, the light will probably pop inwards...?

I checked the dimming **** and that didn't do the trick.

Also, I noticed there is another license plate alike lamp behind the car and I read it's for the replacement tire? When is it supposed to go on? I found that my socket looks brand new there and there was no light bulb in.

 

The courtesy light sockets are supposed to have power all the time....what turns the light on is a switched ground.Make sure the headlight switch is not turned to turn the lights on.

On the dash lights....pull out the headlight switch and put your test light on the "inst" fuse...see if its hot...rotate the dash ****...and check both sides of the fuse.

 

I managed to get the license plate light working today! The bulb was burnt out At least outside all the lighting now works.

I am going to test the INST fuse right away. I will let you know.

 

I had hard time figuring out where the INST fuse exactly is cause the text is quite worn on my fuse box. I think I found the right one - the top left edge 75 fuse. I couldn't get any test light indication through it, I also fiddled with the light **** and rotated the dimming function.

 

The plug and relays in the picture looks like they possibly went to an aftermarket security system.

 

If you dont have power on the inst fuse you wont have power to the instrument lights--next check the taillight fuse.The tailight fuse feeds the inst fuse through the headlight switch....getting a headache yet?

 

LOL. I will check this out then. Additional problem is that I probably can't find that tail-light fuse.

I opened the instrument cluster and removed it. The bulbs seem okay and also the circuit in the back. I removed the light switch and it seems like old. I guess the dimming function may be fully damaged. I took all the wires off the switch with the huge plug. I was wondering if I could just play around and supply 12V to those wires one by one and see when the fuel and other center gauges will perhaps lit up?

Clai1: I'm now quite sure it's all for the aftermarket security system which sits in there partially open etc. None of those wires have power. I'm glad cause then at least the original wires are mostly in place.

 

the dome lights would be a faulty dome light times i assume. you can ground the two white wires together to make them function with the doors only not timed. i made a thread earlier for a theater light timer that you can replace the faulty one with if you choose.

 

I see. I never knew this car has any timer controlled interior lights. Where is the timer located and what does it look like?

 

Timer is located behind the glove box. Take the glove box out and you will find a orange Timer . If you jump the Two white wires , Lights will work but no time delay. Orange timers are about $50.00 to $90.00. I took mine out , jumped the two white wires and called her sweet.Thought a replacement part was a little pricey.Dave

 

The timer above is out of the 80 vette. Dave

 

And if I remember right on the 79 the connectors might be such after removing the orange timer that the white wires will be a male and a female...so you can just plug them together.(no extra jumper)

 

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Let’s not think of the white wires of the courtesy lamp system as a ground, let’s think of them more like a common neutral wire between devices, headlamp switch, door pin switches etc. If you found the timer relay try this. Disconnect it and make a jumper wire of the same gauge as the white wires and connect jumper at the plug connector to the two white wires of the harness. See if lights work normal now, door open lights on, door closed lights off, no time delay. Dave

 

I will check this stuff, thanks guys! But about the headlight switch... you know there is a big white plug going onto it which holds all the wires. How can I test its functions? Can I run 12V through all of those cables separately and see if the instrument lights go on etc?

 

If you just want to see if the inst lights light put 12 to the "inst" fuse. If you feel the need to start at the switch feed 12 v to the dark green wire.

 

my 79 just ties the two white wires together and the lights work like a normal car does.

 

YOU GUYS ARE THE BEST! I solved both of the electrical issues tonight. The dark green wire from the light switch was open and that was the only reason why the lights didn't work. All the center gauges lit up as soon as I connected it to the switch and pulled the ****. I then tested with the instrument cluster which I had removed and all of those lights also turned on. I think one of the previous owners had disconnected the dark green wire intentionally because the circuit sheet behind the main gauges is in quite bad shape. One section under an illumination bulb was especially bad and when I rotated that bulb around, there were a few small electric flashes from the bulb connection, then all the lights went off - the INST fuse broke. After replacing the fuse all the lights were working again but I didn't test with the faulty cluster circuit anymore. I think that must be replaced for sure cause it's broken from several places.

It seems like my light switch works but the dimming function has no effect. I wonder if the dimming is completely up to the single switch and if I replace the switch, should it work perfectly?


The door-opening lights were constantly on because of the timer, just like previously instructed! I connected the two white cables together (I did it within the 5-pin plug, didn't remove it) and the door sensing system began to work! I will now have to think if I want to buy a new timer or just permantently connect those white wires together. I guess I have the whole winter to decide anyway

Fixing the Vette is just so much fun with the help from you guys.

 

Dave