BMW Repair: 2005 BMW M3, rear view mirror, rain sensor

Question
I own a 2005 M3 with the Competition Package. A few months ago I had the windshield replaced because road debris had created a hole the size of a dime; thankfully nothing else was damaged. That said, I had my insurance company change the windshield for me and they sent out a company who replaced the windshield in my driveway. Apparently the people who fixed the windshield did not place the rain sensor back on the windshield. I was not aware of this until I noticed rattling coming from the rear view mirror. I managed to open the housing with ease, and found that the sensor itself was just placed inside with being mounted on the windshield. So I have to ask is there a way that I can mount this thing back to where it was without going to the dealership? What kind of adhesive should I use? I looks like clear caulking to me. Should I use that? Thank you for your input and time. -Michael-

Answer
Michael, should have a little wiring harness that extends from the headliner area to the back of the rear view mirror. From there three wires continue down the black rain sensor (black box with three wire connector). The windshield should have a black area at the top of the glass with a little blue oval or square window that is the optical element that the rain sensor uses. You should see this when viewing from the outside of the car. If you do not have this then the wrong windshield was installed and compare the glass with another E46  3-series car (2002 or later) rain sensor option. Anyway the rain sensor mounts to the windshield by four tabs around the blue element in the glass that I spoke of earlier. NO GLUE! The three wire connector faces the top of the headliner and on either side of the sensor are little black squares at the corners of the top edge that the connector is on. Push them down slightly and you will slide the receiver legs on the sensor down. (they will stick out the bottom a 1/4 inch. Fit the sensor over the four tabs around the element evenly and push the legs back up from the bottom. The sensor is now mounted. Turn the car off for a minute and turn it back on and start the engine. Push the wiper stalk down to intermittent/rain sensor setting and squirt water on the blue element area or put your hand over it. The wipers should active when doing this. If they don't then you have an issue and you should go to the dealer. If what I am describing doesn't look remotely familiar go to the dealer and have them check that correct parts were installed. The rain sensor should have a 354 part number.
I install windshields for the dealership and the work that the sublet mobile windshield guys do is scary to me. Hope this helps. Fill out a survey if you would. Send any repair bill to your insurance.
-Evan