When I first installed my head unit it would not come on at all. I didn't have the ground connection made good enough on the harness I made.

__________________
08 4.0 Sport 4x4
Stock

Yeah check the wiring and make sure its good and secure as well as you have a real solid ground. And did you check the fuse on the deck?

__________________
99 extended cab, 4.0, auto, 33s, 4x4 lifted with some stuff done

98 2wd 2.5, 5 speed, dropped with some stuff done