E Class Parking sensors
 

I have a 2007 E350 Sport, I recently purchased aftermarket parking sensors from Tadi Brothers and want to install them into the rear bumper, Can anyone shed some light on which wire is for the rev lights as I would need the parking sensors to engage when the car is put into reverse. Any advise would be of great help, espically when it come to wire identification. Thank you in advance for your help.