Rain sensor

I have a 2014 LX570 with rain sensing wipers. I never have to touch the switch because they work that good. My question is this, how hard would it be to wire this into our system? The same sensor has been used GX & LX models since the mid 2000's and you can get them on Ebay.

 

I had one on my 2011 BMW 335D. Thing about it is everytime I started the car I would have to turn it on for it to work. Never really figured out the point in that, if you need to turn it on why not just turn the windshield wipers on while you're at it?

 

traditional non- no touch car washes and Rain-X users.

 

Actually the windshield is the same, the sensor is in the unit that attatches to the inside behind the rear view mirror. I would assume there is a relay to go along with thesensor. It's just really handy.