Originally Posted by
Ronman
I guarantee that is the reason. Actually it is either the brake lights will not light up or the cruise control will not work. I learned this in the Mercedes forums. I've had to change mine more than a few times so I know from personal experience. If you have a good code reader it will also say stop lamp inoperable or something similar.
The cruise control will not work if one or more of the wheel speed sensors fails, or if the steering wheel sensor fails, I have forget the name for it at the moment.
If the yaw sensor fails, if the ABS module fails somewhere in the circuitry. If the throttle plate jams. Those are just of the top of my head, apart from the brake switch which I said can cause the same lamp to light.
Nothing is guaranteed like you say, it is possible that the switch is kaput we will see.