1994 Buick Century Alternator issues

Tiny
NATELIENN
  • MEMBER
  • 1994 BUICK CENTURY
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 150,000 MILES
Hello, just got this buick from someone I know. They said the alternator was just replaced, the battery seems to be new and seems to hold a charge pretty well. When I charge the battery then start the car, the voltage will start out normal (14V). Over the course of a couple minutes, the voltage steadily drops, even if I am revving the engine, until it finally dies.
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Sunday, February 8th, 2009 AT 5:46 PM

6 Replies

Tiny
OBXAUTOMEDIC
  • EXPERT
Hello,

You will need to have the charging system checked. If you have a DVOM you can check to see if the alternator is charging. If not go by your local auto parts store and have them check most will do it free.

Check out this link if you want to test it yourself....

http://www.2carpros.com/how_to/how_to_test_alternator.htm

.
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Sunday, February 8th, 2009 AT 6:01 PM
Tiny
RASMATAZ
  • MEMBER
To add check both fuse and wiring -see below


http://www.2carpros.com/forum/automotive_pictures/12900_fuses_6.jpg

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Sunday, February 8th, 2009 AT 6:11 PM
Tiny
NATELIENN
  • MEMBER
Ok, I have checked out the alternator and battery, both are in near perfect condition. It seems that when I turn on my lights, that is when the drain happens. Before the car was given to me, the front driver side was damaged in an incident. I disconnected all harnesses to each headlight/brights. The meter reads about 14.00 V +/-.02. On the passenger side, when headlight is connected, it goes down to 13.30. When passenger bright is connected, goes down to 13.00. When driver headlight is connected, goes down to 12.95. When driver bright is connected, goes down to 12.80. This is all while revving the engine. Are these normal voltages? I now remember the car first dying on me while using the headlights. I have not connected all the harnesses at the same time yet, I just did individual.
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Sunday, February 15th, 2009 AT 6:43 PM
Tiny
RASMATAZ
  • MEMBER
Could be some resistances dropping the voltage a bit but for me its normal. Or you can go higher output alternator to keep up with the load
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Sunday, February 15th, 2009 AT 7:57 PM
Tiny
NATELIENN
  • MEMBER
Well I did some more playin around and it turns out. I dont know. The alternator will go up to 14 V, but when I idle the car, it can sometimes go down to 12.00, usually around 12.40. Is that normal for idling? This is with the lights off.
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Sunday, February 15th, 2009 AT 7:58 PM
Tiny
RASMATAZ
  • MEMBER
Sounds like the internal voltage regulator is not controling the field winding-Pull the alty again and get it reload tested

A good battery will read above 12.4 volts with no load on it-Try this disable the ignition system and crank engine over for 10sec if it doesn't hold up 9.5 volts replace the battery
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Sunday, February 15th, 2009 AT 8:15 PM

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