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My battery light started coming on last week. it isnt driven on a daily basis so it want that big of a deal. Now it won't even start. If jumped it starts right up. But if its just sitting there idling, the lights get dim and the radio turns off. So is it my battery losing charge... or is it the alternator not charging the battery? Help me pls[/quote]

Most likely the alternator. If it was only the battery, it would charge fine after being jump started.

I say only the battery, because possibly the battery has been getting weak, and worked the alternator to death.

It is sort of common to replace a battery that has been slowly dying, and have an alternator fail shortly afterwards.

So I just went to advance auto, they checked my battery and alternator. My battery measured at 1589cca and its rated for 525cca. And my alternator came up no voltage! Whats going on?

The idiot at Advance doesn't know how to use the scanner? Not sure how you triple the battery CCA...

Yea thats what I was thinking

When it's running disconnect the negative battery cable. If it dies, that indicates the alternator. If it is the alternator it's recommended to change the battery out with it or it'll kill the battery faster.

Thats what I thought.. But after posting it on someone elses thread I was corrected and told thats not good for the car or the pcm on modern day cars... Thanks though

Yep, without the battery to stabilize the voltage, the pcm will go nuts trying to keep it at target voltage.

occasional demons wrote: It is sort of common to replace a battery that has been slowly dying, and have an alternator fail shortly afterwards.

oh, shit.

I just changed my battery the other day... the one that was in there was weak since I got the car in January.