Sergio79

Casual User
Oct 12, 2017
20
13
Montreal
VetteCoins
1,210
Car
1979 Corvette
Province
QC
The lights of the dash gages of my 79 vette were pretty much all burnt. I though it would be cool to replace with them LED light. I pull the dash and the console and replace the dash bulbs with LED. Now the console gages (oil pressure, engine temp and voltage only work when I turn the car lights on ....??? Just on day light, the console gages don’t work with the exception of the gas tank gage. I read stuff about the polarity of the LED. Are the LED compatible with the C3 electrical system ? Or did I only f/up the 30 years old printed circuit in the back of the console in removing the old bulbs and re-installing the new LED ? Thank you.
 
The lights of the dash gages of my 79 vette were pretty much all burnt. I though it would be cool to replace with them LED light. I pull the dash and the console and replace the dash bulbs with LED. Now the console gages (oil pressure, engine temp and voltage only work when I turn the car lights on ....??? Just on day light, the console gages don’t work with the exception of the gas tank gage. I read stuff about the polarity of the LED. Are the LED compatible with the C3 electrical system ? Or did I only f/up the 30 years old printed circuit in the back of the console in removing the old bulbs and re-installing the new LED ? Thank you.


Normally polarity is not an issue with LED. The only issue I’ve had with conversions is being forced to add a resistor for things like headlights and cruise control functionality due to the low draws compared to the incandescent system design.
You should be able to simply buy like for like LED bulbs and plug them in. They are available for pretty much any build design. Lots of places to get them online cheap. Google and a bit of forum mining will find you a good supplier quickly.

Good luck.
 
Ive had issues in the past where load equalizers were required, or it would wreak havoc on other systems, since the draw us so low with LED that it plays with everything else in its path. with old gauges, it is difficult to modify them for LED, though i am sure its been done. now i havent looked at my wiring or how the bulbs work, but if they are wired, you have a couple of options. load equalizer on each line, or run a new harness for the just the light bulbs off of the ignition and install one equalizer in the harness( a bit of)ignition will have lights on all the time, from the switch would be more ideal. your gages flatlining without the lights turned on could be something as simple as a ground issue or an issue with the ignition feed, since they should be powered by the ignition and not the light, im leaning more toward something with your lightswitch affecting the circuit.

I remember seeing LED gauge hardware for the C3 online somewhere, but it was a set of gauges that upgraded all. could be an option for you though. the wiring mess that awaits me in a few months on my build terrifies me a little!
 
I added LED gauge backlighting to my 70. It is an amazing upgrade and finally used green LEDS to give an extra nice touch. My only issue is due to the very low current draw, the dimmer hardly works. It is almost too bright at night but better than before as you could hardly see them. You may have a defective rhostat/light switch with your issue.
 
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Thank you for the advises. This will be one of my winter projects. I will reopen the dash again, and re-install regular bulbs. On my 79, all gages and bulbs are connected together with a 40 years circuit board made of a flexible plastic film with imbeded Wires, instead of individual wires. While changing the bulbs last winter I may have created a short. I will get my tester out, get a big coffee mug and exercise my patience. Fun, fun, fun, ...
 
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