No dash lights...What the....????

[714Speed]

Hey guys, I just bought a super clean all original 71 4speed coupe. Only problem is, the dash lights and gauge lights don't work.:confused Headlights work, dome, accessories work. I tried fuses first, then moved under the hood and found a green and red wire lead that goes..........nowhere!:duh It comes out in front of the driver's side firewall in the engine compartment. Right above where the red and green come out, there is a plug-in with no room for it to plug into it. I'm sure this would fix it, but, as you can probably tell, I'm not an electrician. What in the world should I do?:crazy

 

[paintdaddy]

Hey buy a wiring diagram and a assembly manual.Ther are a couple of grounds .Maybe one of them came loose I am currently fixing a burn victim and am up to my ass in dash wires so I might be able to help.

 

[714Speed]

I see you're in GA too. I'm in LaFayette. Is it dangerous to drive it as it is?

 

[paintdaddy]

I wouldnt think so but I would try to get it fixed asap

 

[JohnZ]

On a '71, the dash lights are fed by a 16-gauge dark green wire from the rheostat on the headlight switch; it goes to the fuse block, through the 'inst lps" fuse, and comes off the fuse as a 20-gauge gray wire that comes back to a splice in the instrument panel harness that feeds ALL the dash and gauge lights. The two wires you found hanging (purple and light green) are for the backup light switch connection on a 4-speed car; they aren't used on an automatic.

 

[cmegga]

I have an 81 so Im not sure if things are set up quite the same. But do have experence with this one as it has happened to me three times now. Probably the most irratating thing since I have had the car.

The first go around was the dash switch. The large metal switch behind the dash the one the pull knob connects into was fried.

Round two a few months later was a short in the fuse box, it actually meltied the fuse location from the back, it was where the heavy yellow wire ran down from the metion above switch. That one I let the experts fix.

I made it almost a full year from there until this spring I pulled it out and the dash lights were flickering bright and dim. I had a eigher a bad ground behind the center councel. They ground up top by the vents be hind the guages. Or it was the funny looking harnis that plugs in to the guage cluster in the center. I cleaned up the conection on both while I was back there and the problem was sloved .

Hopefully for good !!

So I would consider or look into any of these three areas.

 

[714Speed]

JohnZ: Where do the wires just hanging there plug up to? And since all lights work except for the dash and gauge clusters, what do you think is the problem?

 

[78SilvAnniv]

Headlight switch.

I have a similar problem.
My headlights and all other lights (interior and exterior) work EXCEPT for the dash/gauge lights. However, the dash lights will come on faintly once in a great while but if I try to adjust them brighter, they go out entirely.
I drive with a flashlight aimed at the tach/speedo.

Husband has told me that this is the headlight switch, but since the dash lights will work occasionally, he thinks the headlight switch may just need to be cleaned and not replaced. Fuses are all okay.

I'd try cleaning the headlight switch and seeing if that solves the problem before replacing things. We will be needing to remove our dash soon and will do ours then.
Good luck with your problem.
Heidi

ps, automatic so I don't know where your hanging wires should go.

 

[paintdaddy]

I would suggest replacing the headlight switch.They are only about $40.

 

[78SilvAnniv]

They are only about $40.

:duh I'm looking in the wrooong catalogs!
Heidi

 

[paintdaddy]

I just checked tld,it says "on temporary backorder" Maybe Iraq is the main supplier of these

 

[714Speed]

When you say remove the dash to put a new light switch in, are you saying take off the top pad as well as the front?

 

[jim coulter]

I removed my dash without removing the pad, but I did have to drop the steering column(or take the chance of breaking the dash) It does sound like your switch. My dash lights quite working and I found the wire that looks like a spring(rheostat)had broken. Could be whats happened to yours. Its worth a look.

 

[714Speed]

Well, when I turn the light switch all the way over as far as it will go, the dome and accessory lights do come on. Does that mean anything?

 

[jim coulter]

Trying to think. Its been over a year since I did mine, but seems like my dome light worked also, just not my dash lights.

 

[JohnZ]

The rheostat that controls the brightness of the dash/gauge lights is part of the headlight switch, and is a wirewound circular resistor; the light switch shaft moves a "wiper" that slides on the rheostat windings as you rotate the knob to dim/brighten the dash/gauge lights. At the end of counterclockwise travel, the "wiper" contact leaves the resistor windings and touches a solid contact terminal for the dome lights and the dome lights come on. The rheostat can be shot (no dash/gauge lights) and you can still have the dome light switch portion working. Sounds like you need a new headlight switch. Sometimes you can remove the switch and find the resistor windings just dirty and in need of a good cleaning with electrical contact cleaner, but usually the tiny resistor winding wire is broken somewhere and it's time for a new switch.

 

[714Speed]

Many thanks

 

[jonstr]

If you're willing to do without the car for a couple days (assuming it takes a couple days to get the switch), pull the dash out and run a quick test before you assume the switch is bad.

Disconnect the harness connector from the headlight switch. Make a jumper wire and connect the dark green wire to the red wire in the harness connector. This should make your dash lights come on full bright. If this works, then the problem is most likely your headlight switch. If not, it could also be the ground connections. I don't recall that you said if this was ALL dash lights, just the tach/speedo, or just the center cluster, but there is a ground lug connection on the back of your speedo and another on the back of the tach. I believe the center cluster is grounded through the bezel assembly.

Jonstr

 

[714Speed]

Thanks for the info, I will check it out asap! I checked with my local auto parts store today and they quoted me $12.95 on a new switch vs $50.00 from all of my vette sources.

Could you tell me which side the ground is on the gauge cluster?

 

[WayneLBurnham]

....and for some more bad news....

I have long since replaced my light switch - and had the dash (all parts) out many times.

Now all the gauge lights blow a fuse in a matter of minutes.

Somewhere there is a grounding lightbulb socket I suspect. I found one once shortly after I got the money pit in the console /cigarette lighter area (which I also have not fixed yet). I went through and used up all the bulbs I had and taped over everything else.

Things worked fine for quite a while, until another short showed up.

I thought *I* was the only one that always had two flashlights in the car!!!!

Next I will take out all sections of the dash and console (again), replace the bulbs and this time use liquid electrical tape all over everything - but I just got through getting around a broken ignition mechanism and remote switch! With the oil sensor acting up and windshield wipers & washers out, the gauge lights seem minor....

I would not think you have a major problem though.

Despite the little quirks of a 30+ year old electrical system, the basics are pretty robust. C3 vette's protect the battery from engine heat, have truly enormous cables that are well secured and only have less well water insulated bulkhead connections than perhaps a 4-wheeler of half a generation later. If you start noticing weird actions on the key when starting or smell insulation burning or can't read key gauges like oil pressure, water temp and charge status then worry about "should I drive the car?" These other things like interior lights are just "extra features" anyhow! :crazy Fix 'em when it's convenient.