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Old 11-21-2012, 06:35 PM   #1
Scooby Newbie
Member#: 292604
Join Date: Aug 2011
Default Is it the alternator going?

I have a 2001 Outback 3.0
The brake light and battery symbol light up only sometimes on the dash. When they do the voltage drops from 14 to less then 12. But they will go off and everything will be fine for a couple days. Then come back on.
Should I replace the alternator? I thought when the alternator goes bad it goes bad.
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Old 11-21-2012, 11:37 PM   #2
Scooby Specialist
Member#: 283815
Join Date: May 2011
Chapter/Region: TXIC
Location: San Antonio
2003 psm wrx wagon
Built Fuji Tough


It might be the voltage regulator going on the fritz. To be on the safe side, I would replace the alternator (the voltage regulator is built in to the alternator). Its cheap and very easy to replace, and at least you will know you have a new alternator, even if it doesn't fix the problem. Carry an ohm meter with you (less than $5 at harbor freight) and check the voltage at the battery next time it flakes out on you if you want to be sure.

Also, double check all your connections at the battery and the alternator too. If those are loose or corroded, that could be the culprit
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Old 11-27-2012, 02:12 AM   #3
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Member#: 30669
Join Date: Dec 2002
Chapter/Region: Tri-State
Location: USA, North NJ, 07456
1998 Legacy 2.5GT
Silver Sleeper BK, 5MT


Check the battery voltage with the car off. It should be ~12.5 volts or better.
Start the car, let it idle. It should quickly come up to ~14 volts.

If the battery is lower (in step 1), charge it for a few hours, then recheck step 1 & 2.
If the battery is OK, try removing the battery ground connection with the engine running, it should still run. If not, the alternator has an issue.

A really bad battery can put a lot of load on the alternator (actually going through this as well on a 1999 Impreza L).
Yes, when the battery voltage is too low, you can get strange lights showing up on the dash. The car may also run rough due to lower spark voltage.
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