Bad Battery or Alternator? Need Help!

I've had my Tacoma for almost a year, and I've been through the battery it came with, and another battery from autozone. Both were placed on a computer and came up with the "bad battery" reading, but that's not my concern. My concern is that the brand new battery I put on there two months ago has already died. That's why I thought it was the alternator, because I didn't think I new battery would be dead after two months. Given, I do live in Texas and the heat here is beyond bearable.

There is a light in my dash that "fades" on and off, it's the symbol of a battery, in the bottom left hand corner of my dash. It doesn't stay on constantly, but kinda flickers on and off.

Anyone with similar problems? I've upgraded the battery for now and the truck is running but I'm afraid I'll be replacing the battery in another 2 months if it's not the battery after all. I've had two diagnostics machines tell me that the alternator is running properly, so the only other thing that comes to mind is a short in my wiring system or a bad cable.....HELP! Any advice will be taken into consideration. Thanks!

 

I had a similar problem after I went mudding in a swamp. The brushes in the alternator are not protected from the elements. I got some dirt and crap in my alternator and the brushes were clogged. I took the alternator off and cleaned the brushes and made sure they sprung freely. Now it's fine. Fried one battery before it got fixed, though.

 

Not true in all vehicles though. Did that test and the truck started dying
but autozone used two dfferent machines and said the alt was fine. I guess I'll just have to take the damn thing apart then and clean those brushes, see if that'll work. I'm on my 3rd battery......so I don't think it's the battery.

 

Oh yea, it's easy to remove and install. It's just annoying....should I replace it even if autozone is telling me it's good?

 

Now that you mention it, there is a wire that is connected to the body of my truck, but doesn't run anywhere. The guy at autozone said it was the ground wire and it should be connected to the negative terminal on my battery, so I kinda moved the wire over so that it touches the terminal. No real visible change when doing that though.

I can get a new alternator from the Zone for 80 bucks, but I don't want a "rebuilt" one.

 

The battery light comes on when the alternator is not producing a charge. Has nothing to do with the battery. So it is definitely an alt problem. I would imagine the brushes get stuck once in a while and the spike from 14 volts to zero volts to 14 volts is what is killing the battery(s). Take it off, clean it up nice, and save yourself $80+.

 

Ok then that definitely sounds like the problem. My battery light was flickering on and off. Is there any special way to clean it?

 

the basic "Insert parts house here" test only tells if the alternator isn't functioning under idle conditions. When the vehicle is under load, the electrical demand is increased, more RPMS means more Sparks per minute, means more drain on the electrical system, run the Air Conditioner and even more of a load engaging the electric AC Clutch.

Dead Battery........

Have you checked the belt & tension, could be slipping around the pulley.

 

I took the alternator off the other day when I took it to Autozone, and when I put it back on it was pretty firm. It doesn't seem to be slipping. When I get a free day I'll take the alternator off and clean it and see if that works.

 

Load test the battery first. After that check voltages at the battery and at the alternator, then report back

 

I know I'm reviving this thread however here's another option........

 

I actually replaced the alternator already and the truck is running fine. I just need a more powerful truck lol.