Hi Steve Welcome to the Forum
I would guess it is one of the horn units that have either failed or are disconnected. Here are a couple of websites to help you find your way around. www.realoem.com a BMW online parts list to make sure you have the correct parts if replacing stuff, just put the last 7 digits of your Vin number in the search box. www.newtis.info BMW Technical Information site same information that BMW Dealers work with. www.pelicanparts.com this one's an American site but great how too's with step by step pictures just the steering wheel on the wrong side.
Enjoy your squeaky Beemer
Dave