My wife drives a 2004 GMC Yukon 5.3L. The battery light was flickering on and off for a while. The truck died about 2 months ago so I took the alternator to O’Reilly and had them test it. The alternator tested fine so we bought a new battery and everything seemed to be fine. About one week ago, it started again and died last night. Replaced the alternator with brand new one today along with new battery. The light is still flickering on and off and the battery does not appear to be charging. The volt meter on the dash does not get above 10 but then all of a sudden random lights (ABS, TC, etc) will illuminate and the battery volt meter will peg 14v.

Any thoughts?

Ok, wanted to come back here and let you know what we think fixed the problem. If you are standing in the front looking at the truck on the left hand side (passenger side) there is a ground wire right near the firewall that is right behind the plastic cowl. That wire was frayed and almost disconnected. We reattached and taped it up and now everything seems to work fine.