Check out my post and look for the "Parking Brake ByPass"One thing to note about the F90BT. You can search high and low and you may not find how to bypass the security setting that doesn't allow you to change destination or watch dvds while driving. In order to do so you must ground the parking break... and then take the black/yellow wire for mute out of the RCA harness coming out of the head unit and put it in the empty spot on the bottom of of wires (empty space between two black wires coming out of RCA leads). This will bypass the F90BT security settings and will work free at all times.
http://www.benzworld.org/forums/w163-m-class/1418841-diy-install-pioneer-avic-f900bt-03-a.html
Also, don't for get about ....
http://www.avic411.com/forum/viewforum.php?f=32
Will