1990 Corvette Alternator issue
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Joined: Oct 2009
Posts: 80
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From: East Longmeadow MA
1990 Corvette Alternator issue
I am having a problem with my alternator in a 1990 corvette, convertible, type 8 engine.
I have replaced it 4 times with an aftermarket remanufactured unit and it keeps failing. The alternator sends a charge to the battery that gets over 15 volts and the car stalls out or stops running. I have returned to the auto parts store and the failed alternator is showing a full load only condition and loads the tester motor to the point where is stops spinning. Performing the test that is called out in the service manual indicates that it continues to be a bad alternator. I have looked at the circuits that go into it and they seem to be testing fine. I have removed the two fuses that send the voltage to excite the alternator and the car will run fine but if either fuse is re-installed a high pitch whistle is produced by the alternator and the car shuts down. I do not see where anything links to any type of power module or to the ECM that would be causing the computer to be sending false information.
I have purchased a rebuilt alternator from GM, Big Bucks, and was hoping that someone may have an idea of where to look before I attempt to install this part.
Thank you for any help you can provide.
I have replaced it 4 times with an aftermarket remanufactured unit and it keeps failing. The alternator sends a charge to the battery that gets over 15 volts and the car stalls out or stops running. I have returned to the auto parts store and the failed alternator is showing a full load only condition and loads the tester motor to the point where is stops spinning. Performing the test that is called out in the service manual indicates that it continues to be a bad alternator. I have looked at the circuits that go into it and they seem to be testing fine. I have removed the two fuses that send the voltage to excite the alternator and the car will run fine but if either fuse is re-installed a high pitch whistle is produced by the alternator and the car shuts down. I do not see where anything links to any type of power module or to the ECM that would be causing the computer to be sending false information.
I have purchased a rebuilt alternator from GM, Big Bucks, and was hoping that someone may have an idea of where to look before I attempt to install this part.
Thank you for any help you can provide.
Le Mans Master
Joined: Jul 2007
Posts: 5,043
Likes: 8
From: Tampa Florida
Always put delco alternators/remy on the 'vette....there are a bunch of high failure rates on other replacment brands.
Done any work to the distributor/coil work before all the alternator over voltage trouble started?
Might want to make sure you have one of these (secondary coil ground bar) installed on top of of the ignition coil's cap: http://shop.advanceautoparts.com/web...S_667381327___
Done any work to the distributor/coil work before all the alternator over voltage trouble started?
Might want to make sure you have one of these (secondary coil ground bar) installed on top of of the ignition coil's cap: http://shop.advanceautoparts.com/web...S_667381327___
Race Director
Joined: Aug 2000
Posts: 11,470
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on my 90, i installed an autozone duralast gold alternator. paid $125, and it's been on the car for about 16-17 months now without issue. it has a lifetime warranty, so if it goes out, i just take it to any autozone for replacement. i once read that these later L98 alternators have about a 4 year life expectancy.
Thread Starter
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Joined: Oct 2009
Posts: 80
Likes: 3
From: East Longmeadow MA
In responce to your posting Engle1147,
I did install an Accel super coil on the car.
I do not remember this part on it but will look.
I did go back to the original set up and had the same problem.
I will look into it prior to install of the new alternator, thanks.
I did install an Accel super coil on the car.
I do not remember this part on it but will look.
I did go back to the original set up and had the same problem.
I will look into it prior to install of the new alternator, thanks.
Le Mans Master
Joined: Jul 2007
Posts: 5,043
Likes: 8
From: Tampa Florida
I'm sure you installed one of these 4 on this page: http://www.jegs.com/webapp/wcs/store...hei+super+coil
I see all of those are offered with a simplified ground strap....which should mean that they have the primary and sencondary grounds to the coil connected internally....so only 2 wires are exposed.
These show 3 extended conductors instead of a ground bar/strap and 2 conductors:
http://www.jegs.com/i/MSD-Ignition/121/8225/10002/-1
&
http://www.jegs.com/i/JEGS/555/40115/10002/-1
I'd reinstall your "old" stock coil and ensure the ground bar strap (similar to the one in the link above) is installed before running the new alternator.
I see all of those are offered with a simplified ground strap....which should mean that they have the primary and sencondary grounds to the coil connected internally....so only 2 wires are exposed.
These show 3 extended conductors instead of a ground bar/strap and 2 conductors:
http://www.jegs.com/i/MSD-Ignition/121/8225/10002/-1
&
http://www.jegs.com/i/JEGS/555/40115/10002/-1
I'd reinstall your "old" stock coil and ensure the ground bar strap (similar to the one in the link above) is installed before running the new alternator.
Le Mans Master
Joined: Oct 2007
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From: Akron Ohio
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on my 90, i installed an autozone duralast gold alternator. paid $125, and it's been on the car for about 16-17 months now without issue. it has a lifetime warranty, so if it goes out, i just take it to any autozone for replacement. i once read that these later L98 alternators have about a 4 year life expectancy.
Safety Car
Joined: Jan 2004
Posts: 3,759
Likes: 8
You might could find a local guy to rebuild it. That may be better than an Autozone rebuild. There is a local guy who rebuilds starters and alternators. I had him rebuild my alternator a couple of years ago for $35.
