installing headunit, the dimmer wire?

Why, in all the cars I have installed head units in,  Does the dash light fuse blow?  Whenever I hook  up the dimmer wire on the radio harness to the headunits dimmer wire, the fuse always blows.  I have gone through probably about 20 different installations no and always end up just not connecting the dimmer wire.  Am I suppose to be using a diode or something here?

what are you doing with the illumination wire? most times i use that instead of the dimmer wireQuad L Handyman services

just dont hook up any orange wires!  thats the best way to avoid the problem, they dont really do much, just dim the radio a little bit when the headlights are on, not pratical at all.

Either don't hook up the illumination wire on the deck like they said, or use the illumination wire instead of a dimmer wire on the wiring harness.  Like pimp59 said all it does is dim the backlighting a bit when the light are turned on.  Unless it's some older Eclipse decks, those you need an illumination wire or the backlighting won't come on at all.  But it has to be an illumination wire or a wire that only shows +12v when the parking light are on, and doesn't change when you adjust the dimmer control.  Dimmer wires usually vary in voltage and polarity when adjusting the factory dimmer control, which will cause issues, in your case blowing fuses instead of frying switches.