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Topic: GEN light on with ignition off.

in Forum: C3 Electrical


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GEN light on with ignition off.

Posted: 6/11/14 11:06am Message 1 of 3
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bcousins
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Jacksonville, FL - USA
Joined: 12/15/2009
Posts: 36
Vette(s): 79 L-82 4-speed. Original block now a 383 with aluminum heads, roller cam and rockers, Edelbrock intake, MSD distributor and ignition module, Speed Demon 650 carb. Rebuilt and upgraded all steering and suspension.
My 79 L-82 GEN light is on with the key off. When I turn the ignition to "On" the light goes off. It stays off when the engine is running. When I disconnect the plastic connector on top of the alternator the light goes off because it powers the light. I get 12.1 at the battery with engine off and 12.7 when running. Bad alternator? Battery is about three months old. Alternator age unknown but I have had the car almost five years so older than that. Any suggestions?


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Re: GEN light on with ignition off.

Posted: 6/11/14 1:36pm Message 2 of 3
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bcousins
Former Member
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Jacksonville, FL - USA
Joined: 12/15/2009
Posts: 36
Vette(s): 79 L-82 4-speed. Original block now a 383 with aluminum heads, roller cam and rockers, Edelbrock intake, MSD distributor and ignition module, Speed Demon 650 carb. Rebuilt and upgraded all steering and suspension.
Never mind, I got it. Read elsewhere that the problem indicates a burned diode in the regulator/alternator. Bench test confirmed.  Replaced alternator for $50 and solved. Now have 14.28 volts while running and 12.8 when off.


Re: GEN light on with ignition off.

Posted: 6/11/14 7:48pm Message 3 of 3
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Adams' Apple
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Duncanville, TX - USA
Joined: 11/8/2003
Posts: 20214
Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas
 I was gunna say 12.7 v running isn't working. Glad you got it fixed! Thumbs Up


Joel Adams
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in Forum: C3 Electrical


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