GEN light stays on dim
07-28-2011, 08:15 AM
#41
Burning Brakes
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.
06-10-2014, 02:09 PM
#42
4th Gear
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I have had PLENTY of bad alts. test 'good' on the bench. Remans these days are all built to minimum standards.... minmum at best.
It's almost always the Diodes on these units whan you get a GEN light. (There are three, if one blows you still have basic function, but the unit is hurt and will eventually let you down.) A GEN light will even stay on after the car is shut off and the key is in your hand. I have seen them short to ground and kill batterys overnight, all the while the car runs fine after a jump. Red Herron, blown or missing light bulb in the dash. The bulb is an important part of the charging system and should be in the there.
Removing them like some folks do is treating the simptom, not curing the disease. This is almost always simple and cheap problem to fix.
It's almost always the Diodes on these units whan you get a GEN light. (There are three, if one blows you still have basic function, but the unit is hurt and will eventually let you down.) A GEN light will even stay on after the car is shut off and the key is in your hand. I have seen them short to ground and kill batterys overnight, all the while the car runs fine after a jump. Red Herron, blown or missing light bulb in the dash. The bulb is an important part of the charging system and should be in the there.
Removing them like some folks do is treating the simptom, not curing the disease. This is almost always simple and cheap problem to fix.
06-10-2014, 02:34 PM
#43
Instructor
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.
Last edited by ThePabst; 06-10-2014 at 02:36 PM.
06-10-2014, 03:03 PM
#44
4th Gear
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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.
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.
1979 L-82 yeehaw
06-13-2014, 04:09 PM
#46
Instructor
10-02-2014, 09:17 PM
#47
Burning Brakes
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.
10-03-2014, 08:00 AM
#48
Instructor
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.
Last edited by ThePabst; 10-03-2014 at 08:20 AM.
10-10-2014, 02:52 PM
#49
Burning Brakes
Any other ideas are welcomed.
Gordon
10-13-2014, 07:27 AM
#50
Instructor
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
Any other ideas are welcomed.
Gordon
Last edited by ThePabst; 10-13-2014 at 10:09 AM.
10-26-2014, 02:06 PM
#51
Instructor
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.
11-01-2014, 08:58 PM
#53
Burning Brakes
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.
08-06-2015, 07:20 PM
#55
Burning Brakes
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.
08-06-2015, 09:42 PM
#56
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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
08-01-2016, 10:55 AM
#57
1st Gear
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Thank you
OK one more thing to try. disconnect the 2 wire plug from the alternator-remove the brown wire and put the plug back in the alt with only the red wire plugged in- now take your 12 volt testlight and attach the alligator clip to the pos term on the back of the alt-take the probe end of the test light and stick down in the hole that you took the brown wire out of. Start the engine-if the test light glows like the dash light did then your problem is in the alt.
08-01-2016, 11:37 AM
#58
Burning Brakes
08-03-2016, 05:22 PM
#59
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]
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