alternator light

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donm
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Your car is a: 1980 spider [carb]
Location: Hamilton. MA

alternator light

Postby donm » Sun Sep 10, 2017 6:16 pm

I have what I think is the original 55 amp alternator and lately after starting the car the red light will remain on for a few minutes. eventually it goes out but is this a sign of potential problems? When the light is out the output shows about 13.6 volts.

This alternator has the voltage regulator mounted on the back. Could the VR be the problem? I've read elsewhere that a "bad diode" could cause this. Where is that located? Is that something I can replace?
1979 Spider
2001Saab SW
2004 Saab Aero
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spider2081
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Your car is a: 1981 Spider 2000
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Re: alternator light

Postby spider2081 » Mon Sep 11, 2017 8:22 am

On the Bosch alternators the voltage regulator can be removed while the alternator is on the car. It is a little tedious to replace. Be sure to disconnect the battery before attempting the removal. The alternators brushes are part of the regulator assembly. They may be worn or oil soaked. There are a few things that can contribute to your symptoms. A loose alternator belt would be the first to check.

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RRoller123
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Re: alternator light

Postby RRoller123 » Mon Sep 11, 2017 8:33 am

Have the battery load tested as well. Free at AutoZone, Advanced Auto Parts, etc.
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donm
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Joined: Sun May 30, 2010 12:40 pm
Your car is a: 1980 spider [carb]
Location: Hamilton. MA

Re: alternator light

Postby donm » Mon Sep 11, 2017 1:08 pm

Thanks, guys. I just ordered a new VR.
1979 Spider
2001Saab SW
2004 Saab Aero
Life's too short to drive boring cars

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nelsonj
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Your car is a: 1972 Spider 124

Re: alternator light

Postby nelsonj » Mon Sep 11, 2017 4:13 pm

I recently did a writeup on replacing the VR in-place. I don't know how to link previous posts, but its under electrical titled:
"Replacing Voltage Regulator with Alternator in place" . The thin red straw from a WD 40 can is a big help.
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KevAndAndi
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Your car is a: 1981 Fiat Spider 2000
Location: Chatham, NJ

Re: alternator light

Postby KevAndAndi » Tue Sep 12, 2017 12:12 pm

I tried the VR-replacement route, and it didn't work. YMMV. I ended up handing the alternator and the new VR to my local rebuilder (Italian immigrant, former Spider owner), and now it works and looks like new.
Kevin
1981 Spider 2000


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