If its not the alternator, what is it?

[97gtpsc]

I'm with slow on the bad ground.... check to make sure the ground wire is connecting to the neg post on the battery... i've have a problem with the rubber boot on the neg sidepost....when u tighten the sidepost bolt it wont tighten the ground flange to the battery like it should... i just used a washer to fill the gap and conduct properly

[JoshsGTP]

check the fuse in the motor bay its called alt. sense, then check the wire from the starter to the alt.

[Fivefingerdeathpunch]

bad battery