Charging System Problem (02' Aurora)

[02Aurora]

I purchased my 02' Aurora(3.5L V6) 3 months ago from a friend. I didnt have a problem with it until 2 days ago. I got in, started the car, and after about 30 seconds I heard a chime and the display said "Battery Charging System" and the battery light came on. Then, after about 10 minutes of sitting there with the car running everything started to shut off once the car kicked into "Battery Save Mode". Now, Im not the smartest man but I did figure that maybe I needed a new battery. I took the battery down the road to have it tested. The battery was fine. The next thing to check was the alternator. So, I had that tested as well and it turns out that it was fine also.
Now Im stuck without a car! What else could it be?

Please Help!
Thanks,
Patrick

[Autobanaurora]

Take it to the dealer, Advance told me my alternator was "ok" come to find out it was half the time. New alternator installed at dealer $500.00 on 98. Seems they can't get to it without taking the entire front end apart.

[tmcnall]

It could be the DIM module - it controls the charging system by pulsing the lines (with varying duty cycle square wave) going into the regulator, which is inside the alternator.

Also check Fuse #38 in the rear fuse block.

Don't ask me where the DIM is - haven't found that yet......

I have a similar problem on an '01. Charge up the battery , it starts fine. The it idles for about 15 min and dies. Then it won't start and the battery is completely drained. Hoping it's not the alternator (although that is the most likely cause) because of the labor involved. Right now, I have another test battery to make sure it's not that.......

Let me know if you fixed it and it was something weird....

[TEX Aurora]

I have had battery and alternator problems- after replacing the battery and alternator I found that the real problem was the Battery Temp sensor causing the alternator to overcharge the battery. The Battery Temp sensor is the red cover on the battery end of the positive + battery cable - has two wires coming out of it. If they are disconnected you get "check charging system" and a battery light. But for me it stopped the 18 volt output from the alternator. Unfortunately the replacement Battery Temp sensor costs $50.