side view cameras

Thanks for the input. That confirms one assumption. I do realize that hooking up past the thermal flasher will cause the screen to turn on and off in sync with the flasher; what I don't understand is, when the signal arm is pushed up or down (rt or lt) how does the circuit know which side to activate, if, as you say, there is only one wire coming from the column?
My next assumption is that there are two wires coming from the turn signal arm at the steering column to the thermal flasher. I just cant figure which two...