Living in the Pacific Northwest, functioning windshield wipers are essential to survival. I tend to keep my in the auto-sensing position, however, when driving home last Friday (in the rain) they suddenly stopped working. There was no response in any of the wiper positions. Fortunately, there was still daylight left and I was on a country road doing 35mph and was able to pull off the road quickly. I turned the car off and then turned the car back on and everything was back to normal as if it never happened. I racked it up a minor and temporary glitch.
And that brings us to this morning. I'm driving 80mph on I-5 heading into Seattle for work. It is dark and raining hard. I have the wipers on the auto-sensing position and they are working perfectly. Again, they suddenly stopped working. Thank god the traffic was light because I had to do an emergency pull over to the shoulder because I could not see anything. I turned the car off and back on multiple times with no success at recovering wiper functionality. Not left with many options, I got back on the freeway and slowly drove a mile to the next exit that had a gas station. I was able to buy a bottle of RainX and apply it to the windshield. By the time I completed this process and restarted the car to continue my commute, the wiper functionality had returned.
My thinking is the wiper motor must be overheating and shutting down but if anyone has any further insight into this behavior, I would be most appreciated. Thanks!
It has never happened to me (maybe 'cause I don't use them much in SoCal, although I take a lot of long trips and have driven in heavy rain from Seattle to the Oregon border), but I, too, always have them on Auto.
My first assumption would be the same as yours. The symptoms make heat sound logical. But, why wouldn't it happen to all M5s?
Could you be missing some rubber strips or insulation that keep cabin heat from getting to the motor? The next thing I would try, is to turn off the interior heat (I know, it will be COLD) and see if it still happens.
It could be dirty contacts on the motor, or a motor that is nearly worn out. Nearly worn out motors (brushes almost completely worn down) sometimes work intermittently, although they usually go south and never return. And, I suppose it could be a motor that lets some water inside it's case.
So I was able to get my car into the local dealer this morning and they were able to take a look at it. It looks like it was a simple replacement of a relay versus the more expensive possibility of the wiper motor. They said it is a pretty common failure. In any case, it allowed me to make it home safely as the weather is worse this evening than it was this morning and wipers were a requirement.
Fired up the beast tonight, it's finally raining in Berkeley. Turn on the wipers, they move about a third of the way up and stop. Now they are just frozen there. I'm going to try it again tomorrow and hope its one of those electrical gremlin deals, but if not it looks like I too may need a new relay.
edit: Just saw the above labor charge. Two minutes later I found this thread with instructions on replacement. I love this board.