Charging system

MATTMCCLURE

MEMBER
2001 OLDSMOBILE AURORA
3.5L
V6
2WD
AUTOMATIC
126,000 MILES

Just had alternator and battery replaced 3 months ago (factory alternator) 126,000 miles. Have noticed recently that dash and headlights will pulsate dim/bright. Got 10 miles from the house and battery light came on then numerous faults (air bag, theft system etc) then “battery saver” came on and heater, windows gas gauge etc stopped working. Car had no power accelerating from a stop. Pulled over and shut it off and it would only click trying to restart. Removed battery and took home to charge but it showed 12.85 volts so I went back and reinstalled it. Car started perfectly and ran for about 6 miles with no problem. Got a quarter mile from home and battery light came on again. Now here I am. I have no clue what is going on. Surpentine belt was put on a couple weeks ago but I would think if It was the belt or alternator the battery should have been dead. Any advice would be greatly appreciated

7 Replies

JACOBANDNICKOLAS

MECHANIC
108,128 POSTS

Hi and thanks for using 2CarPros.

If the light is turning on, I feel the alternator isn't doing its job. With that in mind, you need to check it. As far as the battery, if it's newer, it will recover some of its power if there is no draw on it.

With that, lets start with the alternator. My concern is you mentioned the lights pulsate. To me, that sounds like a faulty voltage regulator. Do me a favor, here is a link that shows how an alternator is checked. Follow it. First, do it without the light being on and if it does come on, check alternator output while the light is on.

https://www.2carpros.com/articles/how-to-check-a-car-alternator

Also, confirm that none of the battery grounds are loose, corroded, or damaged, and check to make sure there isn't a corrosion at the battery.

You will need to use a volt meter to perform the test. Here is a link that shows how it is done. Also, I attached a link that shows how to check battery terminals and service them.

https://www.2carpros.com/articles/how-to-use-a-voltmeter

https://www.2carpros.com/articles/everything-goes-dead-when-engine-is-cranked

Let me know the results.

Joe

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Monday, February 25th, 2019 AT 5:06 PM

MATTMCCLURE

MEMBER
5 POSTS

Thanks so much for the advice. Unfortunately the car is at a garage and not at my home. The mechanic says the alternator is only putting out 9.5 volts and that it’s bad. He also says it’s a used alternator which is very confusing because it was supposed to be a brand new factory alternator. I was reading some things that suggested it could be an inline fusible link. Does that sound like a possibility?

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Monday, February 25th, 2019 AT 5:30 PM

JACOBANDNICKOLAS

MECHANIC
108,128 POSTS

Welcome back:

A fusible link works like a fuse. However, it looks like a wire. When they fail, they don't work at all. If you are only getting 9.5 volts with the engine running, the alternator is most likely the problem.

Let me know if I can help.

Joe

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Monday, February 25th, 2019 AT 5:56 PM

MATTMCCLURE

MEMBER
5 POSTS

So it seems like something strange is going on. The mechanic concluded that the alternator was bad which seems odd that the battery was still fully charged. But the alternator he says he took out looks very old yet was a refurbished factory alternator that was just put in a couple months ago. I took the alternator back to the original place that put it in and so far they don’t feel like that is the one they put in. The car seems to be running fine and it does have a new alternator now. I don’t know if it truly was the alternator and the original place took advantage of me or if it was something else and the second mechanic lied. It really seems like one of the two are lying. Still confusing how an alternator caused my car to act the way it did. I appreciate your advice very much though thanks.

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Thursday, February 28th, 2019 AT 12:54 PM

JACOBANDNICKOLAS

MECHANIC
108,128 POSTS

Welcome back:

When you have work done, always ask for the old parts back. That way, you have a better chance that they are repaired or replaced. It is a law that requires the return part. However, there are some things that have what is called a core charge. Basically, the company that sold the part wants the old one back to rebuild it. If the shop doesn't return it, they have to pay the core. In this case, ask to see both the old and new part installed on the car.

You would be amazed what low voltage will do to today's cars. Everything is so dependent on specific voltages that when it drops too low, anything crazy can happen.

Listen, if you have additional problems with this or anything in the future, feel free to come back with your questions. We truly will have an unbiased opinion because there is no financial gain in selling things.

As far as the alternator, if it was old and you never had anyone else work on it, we have to assume it was never replaced.

Take care of yourself and let me know if I can help now or in the future.

Take care,
Joe