Yeah sounds like a wiring prob, my guitar has the same prob. There amy be a fault in the wire, or possibly in the crimp by the way the wire and the head unit. I got 110W Sony xplod custom fits from Halfords in Ballymena mate, the screws had to angles to fit the factory poistions, but their fine and i'm just usin the factory wirin. Sounds like a dodgey junction mate. Phil.