I am trying to install the avic-x910bt and the manual says to hook up to the parking brake with the light green wire. if i am doing the hard wire bypass do i have to still connect this wire? what is this wire used for? need help asap. thanks

No you don't need to if you are doing a bypass... Ground that wire.

The Parking brake wire is used for "legit" installs. when you pull the handbrake up it will activate all the menu's cause it thinks you are parked!!

Good Luck!

You can also read the instructions to the bypass thread that will answer these questions before you have to start a new thread.