GEN light blinking
Thread Starter
Le Mans Master
Joined: Oct 2005
Posts: 6,247
Likes: 471
From: Glen Allen, VA
GEN light blinking
So, the wife and I took the 79 out for about a 200 mile round trip to a winery with a Corvette cruise in this past weekend, and as we neared home, I noticed the generator light randomly blinking for a split second with no consistency, just completely random as to when it happened. I also noticed the volt gauge dipping instantaneously for the same amount of time as the light blinked. We made it home with no problem, and the car started just fine a little while later when I went to pull it back in the garage. I didn't notice the lights dimming when this happened. Does this sound like the alternator might be going out? As a side note, it might have been doing it the entire trip, but I only noticed it at night. I doubt I would have seen it in the daylight if it were happening.
Le Mans Master
Joined: Apr 2011
Posts: 6,284
Likes: 1,170
From: Hermosa
So, the wife and I took the 79 out for about a 200 mile round trip to a winery with a Corvette cruise in this past weekend, and as we neared home, I noticed the generator light randomly blinking for a split second with no consistency, just completely random as to when it happened. I also noticed the volt gauge dipping instantaneously for the same amount of time as the light blinked. We made it home with no problem, and the car started just fine a little while later when I went to pull it back in the garage. I didn't notice the lights dimming when this happened. Does this sound like the alternator might be going out? As a side note, it might have been doing it the entire trip, but I only noticed it at night. I doubt I would have seen it in the daylight if it were happening.
Race Director
Joined: Jul 2015
Posts: 13,082
Likes: 3,399
From: SW Florida.
Alternators rarely eat brushes. So few amps across them. A rotor, stator or diode usually dies dead, but that built-in regulator can get intermittant. Easy to replace too. Need a stiff pin bigger than a needle smaller than coat hanger to hold brushes in.
Thread Starter
Le Mans Master
Joined: Oct 2005
Posts: 6,247
Likes: 471
From: Glen Allen, VA
I've got the day off today, so was looking forward to taking the Vette out for some fun. I just went out to the garage and hit the key and nothing at all. NOTHING! I got out my multimeter and sure enough, the battery showed 0.0 volts. When we got home the other week, I stopped in the driveway to unload the car and turned it off after our hours long drive. It started right up a half hour later when I went to pull it in the garage, and this morning is the first time I've touched it since then. I've got the battery charging out of the car now, and will take it and have it tested. Then I plan to reinstall in and take the car to have the charging system checked. Will let ya'll know what I find out.
Thread Starter
Le Mans Master
Joined: Oct 2005
Posts: 6,247
Likes: 471
From: Glen Allen, VA
ok, I've had 2 different chains test the loose alternator a total of 4 times, and it tested good every time. The battery however would not take a charge. The most I could get after an hour on the charger was .8 volts. It was confirmed at the store that the battery was no good, so for now, I'm going to take the battery from my C10 which is interchangeable with the Vette and put it in the Vette and see what happens.
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Pro
Joined: Jan 2016
Posts: 502
Likes: 103
From: Reno Nevada
Thread Starter
Le Mans Master
Joined: Oct 2005
Posts: 6,247
Likes: 471
From: Glen Allen, VA
Ok, with a known good battery from my truck in the Vette, of course it started right up, but the GEN light was still flashing. Then, i got out on the interstate and it stayed on, and the volt gauge was just barely below half way. Strangely, as soon as I got off the interstate the gauge went back up, just over half way, but not quite as high as it normally reads. I drove straight to Advance Auto for a system check, and of course the voltmeter was reading right over halfway, and their test showed no fault. Now I need to try to catch the GEN light on/voltmeter showing under half to have it tested. I'm thinking the alternator is dying slowly, because it seems to be getting worse each time I drive.
Pro
Joined: Jan 2016
Posts: 502
Likes: 103
From: Reno Nevada
sounds like a short, or something as simple as a loose wire on the back of the alternator.
What is the battery voltage when checking across the terminals while it is running? If it is below 14 volts, your alternator or possibly your voltage regulator is not working properly. It should be 14.3 volts or so when running.
If it is below this, your battery is fine and something either in the wiring or the alternator itself is not working. After this, check the voltage as it leaves the alternator while it is running. It should be the 14.3 Volts. If not, then the wiring from the alternator to the battery is probably fine and it is the alternator.
What is the battery voltage when checking across the terminals while it is running? If it is below 14 volts, your alternator or possibly your voltage regulator is not working properly. It should be 14.3 volts or so when running.
If it is below this, your battery is fine and something either in the wiring or the alternator itself is not working. After this, check the voltage as it leaves the alternator while it is running. It should be the 14.3 Volts. If not, then the wiring from the alternator to the battery is probably fine and it is the alternator.
