Adam is 100% if your battery light comes on when the car is running that means only 1 thing your charging system has failed. AND if you have loose cables when driving around and they became intermittent that was likely the cause of the damaged alternator DO NOT replace the alternator before the cables are fixed or you may well end up replacing it again. If you get real lucky it may only have blown the fuse that every car has between the alternator and the battery but, this is not common.

Loose cables will leave you with a weak battery. The battery is 12 years old and that the great granpa of batteries . It must be a Yuasa- the only battery I've ever seen last 12 years. The alternator needs power from the battery to energize its electromagnets and not getting sufficient voltage can be hard on the alternator. Fix the cables, it is not hard to do. Have the battery load tested- I bet it is weak. Those little Toyota starters run like a sumbidge on not a lot of juice, but the engine needs power too.

The bad battery connections could be the root of all your problems. They make the alternator over-work and burn out. Fix the whole system correctly, all at once. The guys at the parts store will test the alternator IF YOU ASK THEM TO, and bring it in. Whether it is bad or not, replace the cables or at least the ends. Don't think the foil is a permanent fix.

An alternator can't properly charge a battery with loose cable connections. Fix those before you change out the alternator. Read this post on the easiest way to do it.

http://ricksfreeautorepairadvice.com/how...

Remove the aluminum foil ASAP!

Test each of the battery cells with an inexpensive battery hydrometer from any auto parts store. More than likely one or more has shorted out. /or/ Take the 12 volt battery to any store that sells new ones other than Auto Zone or Toyota dealer and ask for a free 15 second *battery load test to see what the reserve amperage capacity is. Battery amperage spins starter motors not battery voltage

yes it is the alternator the loose cables have nothing to do with it because the car starts up and works so it means the battery is giving out and energy and not having it returned, you need a new alternator.

my battery light came on yesterday so i had it had it checked they said its not the battery and that it might or might not be the alternator, i came home and checked the battery cables and noticed they were lose and wouldnt tighten down so i put some aluminum foil in then so they would fit on snugly til i can get new ones but even that didnt help so im in the process of replacing alternator. but my question is if it isnt the alternator then what could it be and how could i test to see if its that