Both of our cars: a Mercedes-Benz SLK55 AMG and a Lexus ES 350 have the rain sensing windshield wipers. Despite reading the manuals for both cars I cannot figure out how this system works. Yes they work in the rain but why aren’t they activated in a car wash?
I’ve never had a car with this feature, but is it possible that the sensors will not turn on the wipers if the car is in neutral? My guess is that when you go through the car wash, you are told to put the transmission in neutral.
Usually the wiper switch will actually have a “rain sensing” position that you have to put it in. There should also be an “off” position. They also want to prevent the wipers from automatically turning on when they’re frozen to the windshield, so they usually they go out of rain-sensing mode when you restart the car.
Now, you and an asst. get to play with a hose and a Mercedes. This is the best of two worlds. Plus, you get to check it in both neutral, park and drive. I guess it’s both of three worlds. That’s like labeling things one two and c. You get inside so all your asst. has to do is spray until you signal him to stop. I recommend doing this with the windows and the sun roof closed and the blower fan on low speed. You may never know how it works but the people at your workplace can waste about two days talking about it. Then they will talk about you for the rest of time. You will be on a par with that well-known Major who used leather dye to refurbish his wallet and shoes instead of replacing them. He dropped a nickel once and hasn’t stopped looking for it yet.