Testing alternator, charging system light is on?

RAMJACCORP

MEMBER
2002 MAZDA MILLENIA
2.3L
TURBO
2WD
AUTOMATIC
25,000 MILES

The vehicle listed above is an S (supercharged) Battery is good, but the charging system light is on. Tested voltage at battery posts while running, and it was below 13, so it looks like battery isn't charging. I had to remove the charge air cooler to access the connector plug and post from the top. I want to test voltage from the post, before assuming the alternator is toast, but can I safely run the engine with the air cooler removed? Can't access the buried alternator with the cooler in place.

5 Replies

KEN L

MASTER CERTIFIED MECHANIC
47,640 POSTS

You should be able to but if you upload images of what you are talking about, I can tell for sure.

Here is a guide to help with the test:

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

Please let us know how it goes.

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Wednesday, September 6th, 2023 AT 12:57 PM

RAMJACCORP

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23 POSTS

Thanks for the quick response, Ken! I already watched that video - very helpful. I've attached a couple images - hope they're useful. I don't want to risk doing any damage to the supercharger or engine. I think they built the entire car from the alternator out. ;-)

Images (Click to make bigger)

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Wednesday, September 6th, 2023 AT 2:09 PM

KEN L

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47,640 POSTS

You should be okay, if the engine goes to full throttle shut it off, I would not rev the engine. Let me know what happens.

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Friday, September 8th, 2023 AT 3:28 PM

RAMJACCORP

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23 POSTS

Just realized I never followed up with you on this one. The problem just went away one day. I still think that the voltage regulator is wonky, though. Since I can't access the post to run a test on it, I'm stuck with it for now. I was able to get the wiring harness open and gave contacts a good cleaning. It needs a new serpentine belt, for sure.

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Wednesday, May 1st, 2024 AT 3:40 PM

KEN L