m1964

Hello,
Our 2018 GLC 300 has no adjustment for the speed of the wipers.
From reading owner's manual, I understand that the 1 position is OFF, one click forward is the low speed auto sensitive, the next click is higher speed auto sensitive, then next is slow (no auto sensitivity), the last one is fast (no auto sensitivity).

Usually, one click forward works fine except:
last night there was mist, not rain but the wipers kept working, so the blades would chatter over a practically dry glass, because the mist would not accumulate fast enough to make the windshield wet.
The solution was to turn the wipers off and keep pressing one-wipe button, which was not ideal at highway speeds, or to keep wipers ON and keep listening to the chattering noise.

Does anyone know if adjustment to the Auto sensitivity is possible at all? If yes, is that a dealer-only option?

thanx

chassis

Normal function for MB wipers. I don’t like it. I usually used the third click which is continuous wipe at the lowest speed. Or press the stalk button once for a single wipe. Auto intermittent wipe as MB implements it is unsatisfactory for me.

bishop64

Maybe the rain sensor is malfunctioning?
BTW, has this behaviour been like this since new?
Also, the rain sensor needs recalibration even if it is not at fault. Eg when a windshield is replaced, the rain sensor needs recoding.

decorily

I know it's not what you are asking but does your wiper speed automatically adjust speed depending on how heavy the rain is?

mikapen

Which is what they're supposed to do.

m1964

Thanks to everyone who replied!
The wipers seem to adjust to the rain "level". I might stop at the dealer and ask them to look at it. The Stop/start system seems not working either (which I actually like) so there is at least one reason to go to the dealer.
We bought the vehicle certified about 15 months ago, it did not have windshield replaced as far as I know.

I will update this thread if/when I see the dealer.

superswiss

The way it works is pretty standard for rain sensing wipers. They adjust the speed automatically depending on how heavy the rain is, or you can set it to one of the fixed settings. That's kinda the point of heaving a rain sensor in the first place. You can adjust the sensitivity with the first two positions. The only thing different about MB is that it only has two sensitivity settings. Prior cars I owned had three sensitivity settings. Key is to keep your windshield free of grime where the sensor is. I use a 50/50 solution of water and isopropyl alcohol. Something I learned from a detailer. All the commercial glass cleaners despite their marketing claims have tons of chemicals in them that sooner or later leave a film on the glass.

m1964

My complaint is that the sensitivity is too high, not to low, because the wipers engage with even mist/dense fog on the windshield, at the speed that leaves the windshield dry so the wipers kept chattering over dry glass.

superswiss

Chattering wipers is not from the dry glass. It's from dirt, contaminants, Rain-X if you use it or wax from a carwash on the glass. The water just masks that. MB has a special cleaner that removes all that from the glass, or as said, alcohol does a good job, too. For example alcohol removes the wax, grease etc. The wipers themselves also can have dirt build-up. When was the last time they were replaced? Wiper blades don't really last more than 6 months, especially in wet climates. Mine dry out over the summer months here in sunny California with no rain, but they replace them during my annual service, which I happen to do at the beginning of January, so I generally have new wipers when the rainy season starts.

mikapen

​​​​​​I don't like my wipers to take their initial sweep, with a dirty windshield and grit trapped by the wiper blades.
So my habit is to leave them in the Off position until it starts to rain. Then I give them a good squirt, to lubricate and clean the glass, and then set them to automatic.

As an aside, when I get off of a gravel road, a lot of fines park themselves on top of the rear wiper blade. So from time to time I lift that blade to release it.

Brendan.k

The problem has been solved?

Vaboy

You’ve gotten several good replies about your wiper question. Thought I’d add that your Stop/Stop system not working probably means the car is sensing a low battery so it disables that system. My 2018 GLC, delivered in July 2017, started throwing up a “Stop Driving, leave vehicle running” message, or something to that effect, Found out that means your battery needs to be checked. I didn’t even realize the SS System wasn’t working until I drove out of the dealer lot after getting a new battery installed. I stopped by the dealer later that day and asked the service manager why the SS System started working again (I didn’t miss it at all). And he smiled and said “you’ve got a new battery now”. Just wanted to give you a heads up in case they tell you it’s something exotic (expensive) going on with your SS system. Now I’m back to turning it off every time I start it. 😫

W205C43PFL

Also to add is that another possible cause is the auxiliary battery failing, could also cause it to not work.

eddieo45

To the OP, the wax, grease etc. that @superswiss cites makes your rain sensor "think" it's always raining. Unless you have remaining CPO coverage, try cleaning the windshield yourself before having the dealer check the sensor. Also, the chattering wipers might have multiple contributing factors, but quite a few of us have solved the problem by switching to Bosch Aerotwins, which are back in stock at the least expensive eBay seller right now: https://www.ebay.com/itm/363625095145

m1964

Thanks a lot to everyone who replied- will clean the wipers and the windshield, regarding the SS system- I do not miss it at all.
Will be checking battery voltage periodically, and for the next oil change (in 2 months) will go to an indy Euro car specialist and ask them to check the battery.the
The GLC originally was sold in August of 2018, so the battery is approaching its life limit.
Is there any coding to be done when installing a new battery?
thanks

Vaboy

Short answer, yes. Lots of discussion on this forum about that and a lot of DIY’ers will say it’s not required. The battery will work fine with no coding, from what I’ve read, leading people to say it’s not required But the coding “tells” the charging system a new battery has been installed and the charging rate is adjusted accordingly. The idea is, this “registering” the new battery will extend the life of the new battery. The coding does require a special tool to access the registration process and you may find an Indy shop that has that. I couldn’t find a shop that could do that in my small town, so I opted for a dealer install. That killed me because I was perfectly capable of changing it myself. But I felt like it was worth “doing it right” and when I realized my Start/Stop system started working again because it no longer sensed a weak battery, I felt like I made the right decision. By the way, I found no evidence anywhere that the SS System has an “auxiliary” battery or anything else that causes it not to work. Pretty sure it’s tied to your main starting battery health.

m1964

OK, so it is similar to Audis ( had a Q5 before GLC).
The problem is that my wife often sits in idling car and does very short trips that drains the battery more than in average vehicle.

Tim_P

Just a shot in the dark here, but is it possible that the spot on the windshield that the sensor monitors is actually still wet after the wiper goes over it? In other words, are your blades leaving streaks that trigger the sensor? Or could it be water from the roof dripping down on the sensor? Since we can't see that part of the windshield from the driver's seat, maybe that's what's going on?

ajmtbm

I also leave mine off until there is a decent amount of rain. I find if I leave it in auto all the time it often randomly wipes at a couple of drops or even a little fogging.

For sure I believe the sensor is way too sensitive, and the lowest intermittent setting does not have long enough between wipes.

mikapen

An advantage of having the battery installed at / by the Dealer, is that the MB parts warranty covers full replacement (not pro-rata) of the battery for 24 months, including labor when done at the MB shop. .

schroedinger

There isn't a way to adjust it. You can leave them off and just press on the end of the wiper stalk to get a single pass.