Reusing a rain sensor off a BMW?

My truck is old, before they had 'intermittent wipers' -- I had installed a button to wipe ever 30 seconds; which works fine. However, it dawned on me that I might be able to use a rain sensor off a bmw/mercedes/ford/etc

The rain sensor is just a couple of IR LED's aimed at 45 degree angle with pickups at similar angles...
Rather than try to mount up the components at the perfect angles, I thought about getting a sensor off a wrecked car & using it.

Has anyone done something similar? My only concern is that automakers may do something "non-standard" to keep the part from being used in other cars...

Can you identify the connections of the sensor board?
Does it contain more than only LED's and receivers?

I guess the first thing you have to determine is the BMW device detecting rain or is it detecting a dry windshield?

Paul