I simply wired the parking brake wire to the ground wire on the harness and soldered all three together, works just fine for me haha. And if I'm not mistaking I didn't use the illumination wire, but I'm not 100% positive.

 

some decks dont allow you to put the ebrake wire directly to ground i tried this on one deck and it didnt work but the same idea worked on another depends on the deck need to research the deck and see what everyone else does for the ill wire ive never hooked it up in any car i had

 

Install a ground relay. Two grounds from the deck and the one from the harness and you're done. Google it there ate tons of threads here about that issue