it is probably not the hazzrd switch, >90% is the crash control relay. Had the same years back and almost no one knew. I tried many things, new hazzard switch, crash sensor, hazzard relay. Took me 4 months to find it.
Then I found a Service bulletin that describes that a certain number of relays are defective and should be changed.
I replaced it, prob solved.
Some have repaired it, it sits right side of the LKM and crash alarmgeber is written on it, the brown relay
http://www.bimmerboard.com/forums/posts/563223/