I have a 2002 Mazda trbuite that's run well since I got it. But now I feel its totally unrealiable! First I had the battery light come on upon starting but it went out after a few minuites. After a week of this, it failed to start at all and I only heard the clicking sound of the starter. AMA came out and said my battey was faulty and because it was over 6 years old, I didn't question it and had them replace it. A week later, same thing, battery light comes on when starting and goes out after a few minutes. No other power issues. So I took it to the dealer and they ran a set of tests and told me they couldn't find any issues but it was likely a faulty alternator. So 700 $ later, I have a new alternator. In less than a week the issue is back. The battery light is coming on and goes out after a few minutes. So far I've spent a ton of money and still seem to have an issue. Any suggestions what to do next???

 

It may be a faulty plug somewhere. Check the alternator hook up plug. The main ground on the body near the battery should be removed and cleaned. I always recommend installing EXTRA GROUND WIRES as the stock ones corrode. The extra ground wires from the negative terminal of the battery i recommend are: another one to the body in a different spot (like the battery hold down bracket), one to the engine block (starter is attached to engine as well as alternator and ignition coils), a small one to the throttle body, and if you have an automatic transmission, put one to there as well.

 

The battery light comes on when there is power flowing (from the batt) INTO the field windings to create the magnetic field needed to generate a current out of the alternator, when the alternator starts spinning it creates its own current and feeds a portion of that into the field windings, this puts "pressure" on the voltage coming from the battery and stops the flow of current through your battery light which turns off. When your light is coming on it means that there is an issue in the alternator where it cannot create its own magnetic field or one is not being created period, do what Noggin said and check all your connections, this SHOULD be a warranty issue with the dealer now since they did the work previously and it COULD be another faulty alternator, you will have to push them on this since reworks, warranty and goodwill are three words that seem to be missing from their vocabulary.

 

Another thing you might look at is the main relay.