What gage is 'down in the red'?

The gauge(in my dashboard) that shows the voltage has a red zone at the very lowest and at the very highest points. So it's as low as it can go.

You are describing several symptoms that suggest the alternator is no longer charging your battery. One possibility, and usually the most common of course is that the alternator has failed, and you are running on your battery. Yes your car has still started so far, if the alternator isn't charging, you will end up with a car that won't start, or worse yet quits on you while you are driving in the very near future.

You need to have the charging system on your car tested, and an appropriate repair performed.

OOOOOH OK, thanks for explaining that. All I could think was "if it's the alternator then why is it starting?"...but that tells me the battery still has a charge left in it so that's why it can still start even with a bad alternator! The vehicle is quite old and is running on it's original alternator!

Thanks!!!!!

John g...I had another question about this...I haven't gotten a chance to take it in yet but what I was wondering is, if the alternator is NOT changing the battery up anymore...how long will a battery last off the charge that's left in it. I'm wondering because I'm afraid it's going to die on me on the way to Auto Zone! What do you think?

As of today, the thing is still starting right up? Weird, or it seems weird to me anyway!

A batteries total stored energy is rated in "Reserve Power", and is typically on the order of one hundred amp/hours. In other-words, if your vehicle demand is twenty amps of current, the battery will be depleted in five hours. The facts are most of today's cars demand forty to one hundred amps continuously, so depending on how many options are turned on, it could be as little as one hours time. Obviously you have made it further than that already which suggests your alternator is at least producing some power, and could in fact be charging normally but the ability to report the charging level to the instrument panel may actually be what is lost. That in many cases still requires an alternator circuit repair or repair or replacement of the alternator but explains how you have operated the car for this amount of time.

The only problem here though is your expectation that AZ as a viable source for solving this problem. I do not use them as a parts supplier at any level for my business. With them using a strategy where people with little, to no formal training are blindly relying on some type of automated testing in order to circumvent the real skills used by professional technicians, they place us in a position where if we were to try and compete, we would have to not get more training for our technicians, and not invest in the tools and equipment required to completely service our customers cars. There is a cost to the public when we lose the easier work like this, and it goes way beyond the price side of the equation. Yes, one CAN deal with a number of the easier problems by using the AZ's of the world. But what do you do when the problem is more than the AZ routine can handle, and the net result of the "unfair to us (me)" competition they created is that you don't have access to a professional technician and the car ends up stranded for an extended period of time? (This is a REAL problem BTW)

There are quite a number of things that can cause your alternator to not charge correctly, that are all external of the alternator. In a perfect world, losing the alternator jobs wouldn't have an impact on our doing business, so when one of these other problems occur it wouldn't be a big deal. But the world isn't perfect so when we lose the alternators (or whatever) to unlicensed activities and only see the nightmares, our CODB rises substantially. This price pressure has made it more difficult for you to have repairs done as affordably as you would like them to be. It's also made it so complete repairs can only be performed by a handful of shops that have purchased the factory scan tool to support your car, or the dealer that sells the make that you have. (This applies to each and every manufacturer)

Well before I read your post I have gone to AZ and the alternator tested that it was not working. I plan to take it to a shop as soon as they can work me in. The tahoe had not been driven in that week since it first showed the battery indicator light but I just went out and started it. So I suppose that's why it continued to work. I'll update this post after I get it to the shop next week...hopefully next week that is! Some of these shops are a week out...ack...

It was in fact the alternator. Thanks!

Those tend to go as vehicles age. Not a big deal.