Jcrew

I have a 2016 SL400 with what I believe are referred to as “Active Multicontour Seats”. The seats have cold air ventilation and automatically conform to your sides as you corner. A few months ago I noticed a significant reduction in the air being pushed thru the ventilated seat on only the drivers side. More recently I have become aware that the side bolsters aren’t quite as active in cornering as they used to be. I also hear some air leaking as the bolster tries to pump up. This is only a problem with the driver’s seat, the passenger seat works fine.
I’m wondering if anyone hear has had anything similar to this and what was the cause. I’m not sure if it’s the pump, a leak in the line from the pump to the seat or, perhaps, a leak in the “bladder” of the seat causing it to lose pressure. Any thoughts?
TYIA.

crconsulting

Two seperate issues, the ventilated seats use fans to push air thru the seatcovers. The bladders are a seperate mechanism. Could be lines (most likely) or the bladders themselves. It could also be the control unit (doubtful because it appears to be functional) but without XENTRY it might be tough to test.

How do your seat bolsters look? Pretty worn? Do you slip into your car feet first or do you put your butt in first and then rotate/swing your legs in? The first method tends to put more wear & tear on the bolsters….

Here’s how the electro/mechanical parts look, bottom & top of seat

Good Luck

Jcrew

Thanks for the info crconsulting. That’s helpful. Not sure if I’ll tackle this my self or if I’ll take it to a shop. I’m leaning towards taking it in.
The car only has about 22k on it and. The seats look like new.

jrupp

Good luck....it's probably not a cheap fix. Lots of info on this particular problem if you search the forum.

AlphaG

Thanks to the OP I was able to fix an air leak at the exact same spot from the passenger seat of an A217 2018 S63 AMG Cabriolet. I initialy thought the hissing was coming from the passenger speaker but it was the same independent of radio volume or balance and was hissing even when the sound system was switched off.

You saved me hundreds, if not thousands, of dollars!

I also used a 90 degree John Guest fitting designed for 1/4" polyethylene tubing (I think 3/4" is incorrectly stated in the original post). I applied a small amount of silicone plumbing lube to a scrap piece of tubing and lubed the o-rings in the fitting prior to installing in the seat. It was a tight space to fit my fingers into but all seemed to work well.

Thanks again!

hornethandler

I had a problem with my drivers side Active Multicontour Seat as well. This link may help to isolate your issue.

https://mbworld.org/forums/sl-class-...lfunction.html

Good luck!

Edit: I just noticed the OP is from 2022 and I'm a little late to the party. Not sure if the OP's issue is resolved... hopefully so.

jmattioni

I had a 2013 SL550 that had this problem on driver side. Fortunately, it was under CPO and they repaired it. I think they replaced a bladder and the pump. The problem is usually a hose or bladder.

You definitely don't want to ignore the problem. If it goes on too long it burns out the pump.

War Party

I have a related but opposite problem with the ‘dynamic’ seats on my 2015 SL550. All functions work properly, but the active side bolsters turn themselves on occasionally without any input from me. I reset them to the ‘0’ (off) position, but at some random time they will reactivate, and when I check they are set to the ‘1’ position again. It’s really irritating to drive out of a parking lot and have the side bolsters constantly inflate and deflate as you make smooth, normal speed turns. I’m pretty sure that selecting ‘sport’ suspension mode will set that function automatically but it happens when I am in ‘comfort’.

I’ve had the dealer look at it while I was in for my last B service but they can’t find anything and it hasn’t happened while they test drove it. Any ideas? Thanks.

crconsulting

Intermittent electrical issues are always tough to track down, especially over the Internet 🙁
Are you original owner? Any interior work done on the car that you’re aware of? (including installation of aftermarket stereo or other electrical modifications)

I’ve seen similar issues like that happen when wiring has been crushed/damaged or insulation breaks down and will trigger the components to turn on or off at random times or with other components interactions such as what you’re describing with sport mode.

But, of course that’s not necessarily your issue….

With limited access to tools such as XENTRY. I would focus on the least invasive procedures first. Reset electrical functions by disconnecting main battery, re-seating/cleaning electrical connectors and check grounds. etc.. Disconnecting your battery and having to reset your personal settings may be a bit of a pain, but it’s a no cost diagnostic option that can clear up random computer issues. The interaction with sport mode is a clue, and there may be other things that trigger the active bolsters to come on, you just may not have found them yet 🙁



Good Luck

War Party

Thanks for the input. I’m not the original owner (I’m the 2nd) but the car has been very well maintained and documented by the original dealership, with no modifications and a total of 30k miles. I replaced the battery about a month ago so it’s been unpowered for several hours. I can’t see any corrosion or even dirt build up anywhere in the engine bay, battery well in the trunk, or even underneath when I had the panels off to inspect that area during the last oil change. I may be able to do one thing the dealer won’t, and that’s try replacing the electronic module that controls the active bolster function without knowing if that’s the problem or not. That is, of course, if I can identify which one it is and where it’s located.

crconsulting

This thread will help:
https://mbworld.org/forums/sl-class-...lfunction.html

War Party

Thanks!