On mine recently, it was the combo relay. If the switch is bad, you can expect other functions on the stalk to to give problems as well, like the high/low beams or the turn signals.

Unfortunately, I shelled out $124 for the combo relay! And that was a GOOD price!

__________________
2009 ML350 (106K) - Family vehicle
2001 CLK430 Cabriolet (80K) - Wife's car
2005 BMW 645CI (138K) - My daily driver
2016 Mustang (32K) - Daughter's car