Battery or Alternator?

Take it to advance auto they have a free test to tell you which it is.

Never pull a battery (or disconnect one) from a running EFI car. The resulting voltage spike can wipe out electronics. People doing this test are throwbacks who think non-computer controlled cars and cars with generators and our cars are all the same.

I agree with Tim - drive on down to your parts store and let them tell you. Since you didnt post any readings with your DMM, we assume you dont have one so anything we recommend to test will be tough to do.

Good luck.

There are a couple ground wire improvements/upgrades you need to make (if you haven't already), but the problem you stated is beyond that. However, fixing or improving your ground connections is always helpful and probably best to do it immediately.

Ground #1: Buy a 14" negative battery cable (with ring ends that a bolt can go through) and swap it for the stock ground strap between the frame and the block. You'll see why once you get a good look at the crappy stock connection.

Ground #2: Two choices here: Clean up the ground connection on the block that leads to the battery. You can see it under the waterpump. Use some light sandpaper to clean up the bolt, metal connector on the cable, and around any other metal part that contacts the cable. The other choice (and by all means do the one just mentioned) is to add a short negative cable from the negative battery post to the front radiator support area. There are a couple small grounds there already, but even a thick battery cable connector will fit alongside them.

I wouldn't recommend touching a ground with the engine running OR with the battery cables connected.

Sounds like a lot of stuff not associated with your specific problem today, but let me (and probalby hundreds of others on this site) stress how important it is to solve the ground issue first. It is quite unreal how many different problems a simple ground problem can cause. In the end, your charging system will be much better, even if totally stock.

Good luck.

+1 on the free auto store test!

JesusOnIceSkate said:

Thanks very much guys. I'll ground as suggested, and take it to the shop to have the alt tested.

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Just to be explicit, we meant to take it to the parts store for a *Free* dynamic test. If you have a hook-up that's cool. We dont want you spending money where you dont have to (if that's the case, we'd have you spend 5 bucks on a DMM and do 2 mins of testing and go from there).

Good luck.