Just checked under the Dash and unlike the Manual shows the Camera Cable feed from the rear Camera enters "the box" that controls all three Camera's without being split into Yellow (video), DC12V and White (Audio).
Back to the drawing board.
Sheree & Michael NCNG LTC(ret) with Munpi and Sheba (cat).
2016 Vegas 24.1 E350 5 speed "Ms. Enterprise", Bug-Guard Screen, Recliners, Infotainment Center, HUD, ARC Shower Rod, Safe-T-Plus, Curt SpareTire Mount,Tornado Black Tank Rinser, ext. WiFi Antenna, Roadmaster Tow Sys& Invisibrake.