Hey e1dorado,

I recently got a 2015 S550 coupe and facing the same issue as you faced in the past w.r.t. the steering wheel button not illuminating at night. I took the car to dealer and they think the multi-function switch (part number 22290076089051) is faulty and want to change that part. I saw your post where you mentioned the contact plate was faulty in your case and you were able to resolve it by changing the contact plate. I don't know if I can trust the dealer or not, wondering if you have any update on your repair and whether you think multi-function switch might be the faulty part. Any advise/feedback is appriciated.

Thanksm
Kooli