Generator Light Will Not Go Off

davidg8991

Well Known Member
Still having problems with my generator light. Cannot get the generator light to go off while the engine is running. I just replaced the "voltage regulator" and "coil". The generator has been rebuilt about 50 miles ago. New wiring harness. Per the shop manual I checked the generator ground by grounding the "field terminal" while the engine was running and the light still stays on. Any suggestions would be appreciated, thank you.
 

davidg8991

Well Known Member
Yes. Per the instructions I used a jumper wire and touched the armature terminal and battery terminal together for about a second or less. I did notice a small spark while doing this.
 

Junky

Well Known Member
On my Corvair, the generator light will glow dimly at an idle, and will go out when the engine is reved. I "stole" this explanation from another website, and it explains how the light works.
The ignition light is used to tell when a generator (or alternator) is charging the battery. When the light is on, it means that you are running off the battery or discharging the battery. When the engine is started and the speed of the generator is sufficient, the light will go out, indicating that you are not running off the battery. The generator is doing it's job and charging the battery at least as much as is being drained. At very low engine rpms - like at idle - the ignition light may flicker or glow dimly. This indicates that the generator is just not charging enough.)

If your light doesn't respond to the increased speed of the engine, it is possible that the generator is defective. With a generator, you can disconnect the negative battery cable while the engine is running, and if the generator is defective, the car will stall or die. DO NOT do this with an alternator, since you will blow out the diodes in the alternator. I make this distinction, because how an alternator operates and a generator operates, is totally different in the way that they produce current. You should also check to make sure that all ground straps are tight and attached to clean metal. I have seen where the dash grounding strap is missing or not properly grounded causes problems with gauges that depend on a proper ground, such as the fuel gauge.

If you want to read the full explanation of how the generator light works, click on this link... https://www.gomog.com/BLAIR/tech/melectrical/ign-light.html
 
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Don Jacks

Well Seasoned Member
Supporting Member 3
Generators don't put out much until the engine reaches about 2,000 rpm.If you Junky's still valid test make sure that you're running at fast idle.
 

davidg8991

Well Known Member
I did what you said. Started the engine and pulled the negative battery wire off and the engine stopped. The generator is newly rebuilt. I bought it off of ebay. I might have damaged the generator by putting oil; down the oil caps, front and rear, not knowing that sealed bearing were used. Is it possible that I can take the generator apart and clean my mess and still have a working unit?
 

Don Jacks

Well Seasoned Member
Supporting Member 3
I did what you said. Started the engine and pulled the negative battery wire off and the engine stopped. The generator is newly rebuilt. I bought it off of ebay. I might have damaged the generator by putting oil; down the oil caps, front and rear, not knowing that sealed bearing were used. Is it possible that I can take the generator apart and clean my mess and still have a working unit?
Yes,it's possible that you messed up the brushes with that oil.If you find them oily ,replace them and clean the armature with a mild solvent.You could even use rubbing alcohol.
 

El Rat

Well Known Member
My guess is bad or no ground(s). I have grounds on:
• both valve covers
• battery to engine
• MSD to frame
 

1964SuperStocker

Well Known Member
Supporting Member 3
Are you using a separate AMP meter and a Volt meter while its running to know what its actually doing? Light could be bad too but I always use external gauges to ensure my car's gauges aren't going bad. Just wondering.
 

Junky

Well Known Member
I did what you said. Started the engine and pulled the negative battery wire off and the engine stopped. The generator is newly rebuilt. I bought it off of ebay. I might have damaged the generator by putting oil; down the oil caps, front and rear, not knowing that sealed bearing were used. Is it possible that I can take the generator apart and clean my mess and still have a working unit?

This sums it up, the generator isn't putting out any current. You should take the generator apart, and wash down the armature with non chlorinated brake cleaner, and blow it dry. Check to see if you got any oil on the fields also by putting your hand inside the case. If you did, then do the same by spraying the brake cleaner inside of the steel case to wash away any oil. Purchase new brushes, install them, and complete the reassembly of the generator. If you have a local Autozone, O'Reilly's, Advanced Autor, or similar store nearby, take the generator into the store, and ask them to put it on their machine to check to see if there is any output. If there is no output, that means that the armature in all likely hood is defective. It is extremely rare to have the fields go bad, unless there is a broken wire. If you don't feel competent to do the repair, see if there is a local shop that repairs starters, alternators, and generators, and ask them to fix it for you. They will have the expertise to get it working again. Before you leave it, get some sort of estimate of costs. If you still have your original generator, take that with you for parts, should some major component be defective. Also, don't leave it behind when you pick up the repaired unit. You never know when you might need another part off of the old generator. Even keep the defective parts, with the exception of the brushes. Armatures can be rewound to work again. Generators are rapidly disappearing from the landscape of old cars, and there may be a time that you can't find even the simplest of parts.
 

davidg8991

Well Known Member
Took the generator off the car and upon inspection found that the brushes were not riding on the armature. I don't know why!!! There was very little oil inside. I guess that I did not make as much of a mess as I thought. I cleaned the surrounding surfaces and adjusted brushes back to normal. Put everything back together and started engine and still the light will not go off! HELP!
 

Junky

Well Known Member
Remove the negative cable again, and see if the engine stalls. If it does, then the "rebuild" might not have been done correctly... i.e. defective workmanship or parts. Also, remove the cover from the regulator and check to see if the points might be burned or sticking.
 

blkblk63ss

Well Seasoned Member
Supporting Member 5
Took the generator off the car and upon inspection found that the brushes were not riding on the armature. I don't know why!!! There was very little oil inside. I guess that I did not make as much of a mess as I thought. I cleaned the surrounding surfaces and adjusted brushes back to normal. Put everything back together and started engine and still the light will not go off! HELP!
So polorize it now since it wasn't charging with the brushes out of position.
 

davidg8991

Well Known Member
The light still stays on after polorizing. Removed the (-) battery cable while the engine was running and the engine stopped.
 
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