Oh you also don't need to hook up the speed sensor wire or the reverse light wire. The reverse light wire is just if you are going to use a camera on the back for going backwards so the radio knows when to turn it on. The speed sensor wire is just kind of a back up in case you lose the satelite signal under a bridge or something like that then it can still calculate your arrival time. Also once it is hooked up and your messing around with it reset the calibration. I forget the exact terminology, but it lets the computer recalibrate Which way is North, South, East and West. HTH Call me if you have any more questions. Dave 847-875-8153