Thanks for the info. I'll check with my local dealer to see if I can get a new contact. I'm pretty sure that's what it is since it works when turning the wheel.

 

I had the same problem, but was able to clean up the contact and ring without buying another. I put a small amount of dielectric grease on the ring as well.

Be careful if driving with no or intermittent horn, there are a lot of bad drivers out there that need to be woken up by a horn sometimes.