I have no idea whether this is normal or not, but my wipers (front and back) will swipe once every time I start the car. This is pretty annoying, and I would like to figure out how to stop it. Is this normal, is there a setting somewhere?

 

Is the windshield dirty or wet?

They may be sensing "rain" ... Something triggering the motion sensor

 

No, perfectly dry, it rarely rains here. But it could be a faulty sensor, but odd that it only does it one swipe and only on startup. So, I take it that it is not normal?

 

Yes it is not normal. It is like PeterUbers said - it will wipe once only if the windshield is dirty or has some raindrops on it.

 

Yes, there must be something wrong with the sensor because it rarely rains and the windshield is spotless. But if it was sensing something there it should continue but it just goes once, wipes a clean, dry windshield, then stops. Very odd.

 

I have both a 2006 ML350 and a 2010 ML 350 and they act slightly differently with regard to the wipers.
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The 2006, with the front wipers in "Auto" will wipe one stroke when the vehicle is started. The way it was explained to me is that the sensor is looking for a "differential" and will do the swipe to identify a new baseline as too what a clear windshield looks like. The real will do one swipe when the vehicle is p-laced in reverse to clear anything that might be there to give the best rearward vision.
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This behavior is stopped when the wiper control is placed to "off".
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The 2010 will not swipe upon start up, but I am told that that was a new feature/refinement for the 2010 year. The downside is that the windshield will become hard to see through before the first time the wipers come on & I find myself cycling the wiper control to prompt the first swipe.
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Hope that helps.

 

My ML is a 2006 . The wiper switch is on "Automatic" all the time .
When I start the car the wipers do not move unless it is raining .

 

OK, on my 2008, I switched it to off (the oval icon) and it seems to have stopped, thanks!

 

Same for my 2007. And if you are in reverse, and the front wipers are working, the rear will activate as well.