moaning

Hello people..

I have a 2004 gmc jimmy 2 dr, 4x4, auto

when at slow speeds and my steering slightly turned i hear a low moaning, or long "ERRRRrrrrrrrrr" sound. Me and my dad tried figuring this out but had no luck. It doesn't happen all the time and when it does its usually after i've been driving for awhile.

:runaround: I love my truck but it's getting on my nerves :runaround:

sure hope you guys can help me............

oh, my power steering fluid is full, i checked..

anybody!!