Hey guys i allready searched and could not find any scenario like mine. i installed my AVH 4000. i used the onstar wiring harness although my unit does not have onstar. it is 2007 gmc sierra classic. the unit works fine until i turn the volume up to about 15 then it goes silent and i hear a click every 2 seconds i have no idea what is going on. I am pretty sure everything is wired correctly please help guys.