Alternator question

Old 01-14-03, 12:07 PM
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Alternator question

I brought my truck to Autozone to have them check the alternator and battery. Battery checked out fine. They check the alternator by amps and not volts. Said it was putting out 34 amps on a 100 amp alt. Said I need a new one. Took it off, went to Napa to buy one and he checked it out and said it is putting out about 14 volts, and it is fine. Who do I believe. I'd rather not spend $150 unless I know for sure what the problem is.

P.S.- when I hit the buttons for the plow when going down the road, the truck really loses power.
Old 01-14-03, 12:28 PM
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The type of truck is???????????

Do the charging system output test in my "The Basics" below. If it fails that, replace it with an OEM marketed rebuilt and be done with it.
Old 01-15-03, 10:07 AM
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If NAPA isn't checking amps under load he's doing a BS check. The alternator can give correct voltage a low amps and will slowly drain your battery.
Joe is absolutly right about the OEM rebuilds!
Old 01-15-03, 02:03 PM
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my .02

I believe that if amperage is being tested at idle, you'll see a low result. I think that the test should be done at 1200 rpm or above.

Someone tell me if I'm all wet.
Old 01-15-03, 05:36 PM
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Autolibrary or a service manual has the test procedures. Simply follow that

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