How would you go about testing out a headunit to be sure it turns on before taking apart your whole dash and everything specifically the d3 just need to test it to make sure the gps works and that it powers on...

 

You'll need to do a few things:

1) Get a 12 volt power supply or a charged auto battery
2) You may need to do this outside so you can get a line of sight to the satellite
3) Strip back your yellow, red and black wires on your main harness and plug into the back of the deck. Hook up the yellow and red together and connect to the POS of the battery/power supply. Black goes to NEG.
4) Grab a speaker and test it on at least one pair of speaker wires (white+ and white w/black- etc...)
5) connect the Navigation antenna and face the antenna 'puck' skywards
6) To test the radio you will need an antenna. Some crumpled up tinfoil will work temporarily in the antenna input.
7) To test video you will need to ground the green wire and move the mute wire to another location and ground that. Details for the last bit are here: www.avic411.com this will bypass the video playback feature.

I think thats about it. To test pre-outputs, you will need an amplifier.

 

^^^^ he wins