[mikegett]

Are you placing the unit in the trunk or front of the car. If you have it in the trunk just splice onto the wire going to the back up lamps. If you have a meter you can just push through the insulation of the wires going to the trunk. You will want the voltage that changes as the brake is pressed. If you are in the front of the car, there should be a sensor located on the gear shift. Pull off the console trim and look for it. It is possible that GM is different, but my ford and honda a proximity sensor located right on the shifter. Once again, if you have a meter you can check to see if it changes voltage (probably drops to nearly zero) when in park. If so, just splice it there. I have no idea what the speed sensor is. How does it refer to it in the manual. The only thing I have seen for dvd and navigation is a reverse lamp and your parking brake that need to be wired.