I've occasionally had luck spraying Deoxit Gold into electrical connectors, to deoxidize them providing a clean contact. Sometimes it has solved strange electrical problems. Not always, but it may be worth trying.

 

My Gen light is doing exactly what you described. It is staying lit even when the car is off and key removed. Do you think that it is the diodes as well? if it is do you have any tips or tricks for removal and replacement.

 

Your best bet is just replace the alt. (The alt has the diode set inside). Just buy a new one and swap it out. I am assuming that your Vette is at least 'decent', if that is the case, you can NEVER go wrong with a new modern unit that will provide more amperage. Don't go nuts though, they make some crazy stuff these days to power big sound systems. !!!!Disconnect the battery before you start!!!!!

If you are not particularly handy, it's still a very basic repair completed with simple hand tools. Rule of thumb,,, re-mans are for chumps that like to do things twice.

Now if you are adventurous, you can get a rebuild kit for about 20 bucks. It's a fun, fiddly project and if it doesn't go well you really aren't out much. There are plenty of vids on YouTube that will talk you through it.

Good luck, your in good shape.

PS
You defiantly want to disconnect your battery until you square this issue up. It's rare, but your battery is 'working' if it's dying. Battery behind the seat? That means Hydrogen gas build up in the pass compartment overnight, not cool.

 

Thank you for the words of wisdom. I will look into the rebuild kit and let you know how it goes and if anything else comes up.
1979 L-82 yeehaw

 

looks like I'm going to have to replace my diode trio as well.....I have the same problem as the OP

 

Late 70s' L-82, I gots me one of them too. Full on Smog Monster,,, but I love her anyway.

 

Glad I stumbled onto this thread, I have the same dim light issue on my '81. I use a battery cut off switch to spare battery drainage but I'd rather fix it completely. I'll have to shuffle my cars around so I can work on this issue.

 

Just incase anyone else is having this issue, remember, anything electrical you 'add or upgrade' puts additional strain on the alt and battery. Going to modern electric fans is a big issue for that aging twerlee Bird. Big sound systems and cellphone chargers need big amps. Often, an old alt with worn brushes, tired rectifiers and diodes are not putting out enough juice to keep up, its making heat, not power. Depending on your location that old alt. has been frozen, cooked, baked, and then frozen time and time again. The Jolly Green Giant treats peas better...

It's a good idea to spend a few extra bucks and jump up to a NEW* 80 amp (Or better) unit.

Also, grounds are at a premium in these cars, clean clean clean... It never hurts to add grounding straps. If you painted, powder or clear coated any of the brackets, be sure that all contact points are cleared of finish, your brackets and mounting points are part of the ground system.

Another good idea is to add a fused, modern battery bus off the positive side of the battery. Use automotive grade 8 gage wire minimum, red in color. Any decent auto sound shop and the internet has hundreds of offerings and plenty of help with that. Wire your new stuff to that, not the fuse block or alt. That original harness was NEVER designed for the demands we put on then these days.

*Re-mans are for chumps that like to do things twice.

 

Well I wasn't quite as lucky on this one. Rebuilt the alternator but then it wanted to continually charge my battery at 17+ volts. So I bought an 85 amp alternator and the measurements at the battery are correct but I still have the dim battery light. Although this car only has 46k miles it did sit a lot in Illinois and 13 more years in GA before I began working on it this year. My next step is to chase down all the ground connections and make they are clean and tight.

Any other ideas are welcomed.

Gordon

 

A 'very' dim gen light is not a big deal. The light is an important part of the charging system and can glow slightly under load. If you are getting about 14 volts to the battery, all is well. Unless it gets on your nerves, I'd let it be. You could try a different bulb, it may be out of spec. and the filament my be offering less than optimal resistance. Also, assuming that your wiring is 'vintage', is a good bet that there is a bug or two in the mix. If it starts and runs all the time, your ok.

 

Hey! I may have found a solution for you! I was working on the center instrument console on my c3 today. The instrument light next to amp gage could be bleeding into the gen light window. You may not have a charging issue at all, it just may be light leaking.

 

bad ground

 

I appreciate the responses. I hope to dig back into this issue soon. My battery seems to be charging fine since I replaced the alternator. I did a complete frame off on my '64 and I'm beginning to think the electrical and vacuum issues on my '81 would be easier to solve if I went thru both systems entirely. I will be sure to update this thread as I make any progress.

 

Hi is this thread still alive? I have a similar problem but I have not power from ign to brown wire.

 

The electrical issues on my C3 were solved with the new alternator. I have other connectivity issues yet to chase down that I think will only require cleaning connections in my gages.

 

Yeah brand new alt same problem new volt meter, new printed circuit board, pins clean, new pigtail on alt. no power to to volt meter when key is turned gen light activates when started but not key turned on

 

This solved the problem in my 78' Delta 88. This ruled out a wiring issue and after I swapped out the alternator, my GEN light issue was gone. Thanks for posting this!

 

Yes, solved my issues after replacing the alternator. Now working on HVAC system.

 

alt's are so easy to rebuild,any 12 year old can do it,,you just remove the alt,set it on its pully,remove the 4 screws on the outside[mark a line in both halfs-so you can clock/line it up to put it back together],then pull it apart,inside of the back 1/2 is the diode trio,the reg,the brushs,and rear bearing,there are 4-6 screws holding everything together,just take everything off,and replace with new parts,[put a little grease on the rear bearing]a trick to hold the brushs in the holder is to push a tooth pick thru the hole,reassmble the rear housing to the front[line up the marks] and put it back on the car[yes ive made it look easy,but it really is]