I have no what is causing this, but there is no power at the harness for the headunit. I am talking about the orange wire, which is supposed to be a constant 12V supply for the memory and stuff. The yellow switched 12V works fine though.

What fuse would I check for this wire? I know the 15A radio fuse is for the switched 12V, and I checked almost every fuse I could find, so maybe I am missing something.

Would it be safe to run a wire straight from the battery right to the harness, just to test the headunit?

When I test the orange wire at the harness, it only reads .5 volts. What could this be????

 

did you check for fuses under the dash and under the hood? I like to check fuses with my DMM set to audible continuity so when i probe each fuse it will beep letting me know if the fuse is good. however you could just run a new constant from your ignition harness or from an availible output on your fuse box if there is a open 12v constant, ive seen a product called "add a circuit" at autozone where you remove a fuse plug the unit in and put your fuse into the unit which then has a wire comming off. If you want you can add a inline fuse to whatever wire you run but the deck is still fused with the fuse that comes on the deck itself.