Originally Posted by JCL

The answer is on the board, I just used the search function.

Read this thread:

http://www.xoutpost.com/bmw-sav-foru...t-upgrade.html

For reference, killcrap is a dealer technician, and so his explanation should be considered reliable. Short answer is no, you don't just need a switch, you also need a new light control module (LCM), a new windshield with a light sensor installed in it, and coding of the vehicle. See the link for details. Note that those prices are, I believe, for a different model, not an X5. You could use realoem.com to get a sense of what US prices are for the parts required.