^ its that kinda crap that makes me pull every aftermarket head unit out of a car i just get and re-install it even if there are no problems. its amazing what kids, hell, even shops will do to get a head unit installed and "working"
My z, the switched power was tapped off of the dimmer switch, and the constant was tapped off of the a/c blower. So you had to have the headlights on, and the a/c on to get the radio to play. The ground was wrapped around the antenna wire.
And I've seen scarier shit stuffed behind a headunit before.