Last night while it was raining like hell I was trying to use my automatic rain sensing wipers that I have on my 450h but I wasn’t able to turn it on, it appears that when I click the auto wiper button, the green light doesn’t even turn on. The last time I used the rain sensing wipers function about a month ago it was snowing but I’m not sure if that might’ve caused it to break or anything because I’ve used it during a ice storm and had no issues.

 

If the green light on the wiper stalk doesn't come on it's most likely an electrical issue of some sort, which is rather strange if the wipers still operate, just not in rain-sensing mode.

I presume no alterations have been made recently in the overhead unit where the rain sensing unit that is attached to the windshield is connected to the car's electrical system.

 

Correct, I have not done anything to the car since I purchased in December

 

Maybe a relay, or possibly a fuse but I rather doubt the latter. I may very well be that the sensor itself has failed.