Truck Forums - Battery/Power Steering problem

I know this is a truck forum, but was hoping maybe we can come up with something.

My brother has a 2000 Camaro V6 3800. Last weekend it wouldnt start on him. No cranking no nothing. So he tried it again and it fired up. The check engine light came on and he also noticed a whine through the speakers and the radio lights dimmingback and forth. The next day it wouldnt start again and so we hooked the jumper to it and fired it up. The next day wetook it toadvance where the battery tested bad but the charging system checked good. Than it was off to walmart (where the battery was purchased) and the battery and charging system checked good. Didnt have any problems with it starting or running or anything for a week. Today he took it to walmart where he goes to school I guess for the hell of it. The battery tested good. The guy checked his power steering fluid and wasnt showing on the stick. The guy told him that if the power steering pump is going bad sometimes it will cause the ground loop through the speakers. I had never heard of that before but besides it being the battery or alternator Im stumped. Anyways hopefully someone can come up with a solution or Argon has some experience with this. Thanks for all the help guys!