Hello all I recently picked up a 2009 S450 4Matic, the car is great and just one thing I cannot figure out is that the seat inflation functions. When I start the car, all function works on both front seats, every bladder inflates, massage and dynamic seats also function fine.

After around 20 minutes of driving, all the bladders still holds all air, but it cannot be re-adjust again and none of the massage and dynamic seats works. Every adjustments turns back to 0 when trying to adjust.

If I stop the car and restart, everything works again for another 20ish minutes.

I have look through almost all the threads on the forum and seems most of them doesn't work is either because of the pump or leaks but mine seems to have no leaks since everything inflates and holds air and pump works fine for the first 20 minutes when starting the car.

Does anyone experienced similar problems? Thanks in advance!

 

SEARCH ?

https://mbworld.org/forums/s-class-w...g-fixed-b.html

 

This has been exhaustively covered at the above link, but in short I'll say I've got the exact same problem as you. Most of my system has been replaced with new parts. It seems to be a software issue of some sort, that does not seem solvable. I've given up, and enjoyed the seat for 20 minutes and am content to wait until I turn the car on/off again. I don't think you are going to figure this out.

 

ha - I was on that page - remove the seat back and pop off all the electrical connections and plug back in - seems to do as much as flashing with later software - these days I think its just as likely a leak somewhere

and or "its a design feature" to quote BMW's catch all for we have no idea how engineers back then made cars work - let alone - we must never allow the public to realise the accountants insist we no longer engineer them to be remotely reliable...

 

Yeah I have read this before and I have taken apart basically everything I can with removing the seatback, I originally did hear some hissing noise and found the T connector is leaking on the driver side and I replaced it. I did not reset it with Xentry but I did reset it with an aftermarket scanner which actually gave me a code for both seat module. Is been around 1.5 months now and is still doing the same as I described.

I tried to hear if any air leaking noise in the middle of the night and interior wise I really cannot hear anything with both seatback cover off. Could there be a leak around the pump also?

 

Leaky system.

 

There could be a leak all over, but Xentry should tell you that. But like I said, even if you track down every problem, your seat will still turn off after 15 minutes or so, and not turn back on until you cycle the car on and off. Sometimes it works twice, something zero. But most often once. So if you are that far, I'd just not bother as you are unlikely to improve your situation. If you happen to fix it where it works reliably, that would be amazing, and please report back here what you found.

 

oh, yes massage takes a rest after 15 mins - it will come back later, u don't have to key on off the ignition - it just needs a break - not sure how long, pretty sure it will be back in 15 or 30 mins time

its funny they make these strange little booklets that come with the car they tell that you how it works and why it does stuff - in the olden days people would read it - nowadays younger generations believe you need to use a telephone to go on a forum where people with no idea can waste time sharing their incompetence with a wider audience - somehow these youngsters think it makes them progressive and more intellectual

 

In my case, and I think the OP case, it will never come back on. Like on a three hour road trip, it will not work again until a cycle on/off. It is frustrating.

 

If you have access to the simple scanner like iCarsoft MB II you can read the error code for the air pump/compressor. If it says it cut off due to over heating it means you have a leak at the air reservoir Pump is protected from burning itself up because of a leak. I had this with the air reservoir safety valve leaking. The pump worked for a few minutes and then went off and the result was that when trying to adjust seat the settings returned to zero. I think this is when the air reservoir does not have enough pressure in it.

Also, when my pump went out it would not come back if I re-xtarted the car right away. I had to wait ~10 minutes for the pump to cool down before it would re-start again.

My air reservoir pressure safety valve had popped and for the fix I had to replace the whole reservoir. MB would not sell just the valve though it is very easy to change out if you would have a replacement valve.

If you have a leak in the reservoir, you should hear it especially if you take that set back liner off in the trunk. This is easy fix if it indeed is the leak at reservoir.

 

Yah, I've actually got Xentry. There are no codes, and almost my entire system has been replaced at the dealer including the pump (twice). It is just ghosts in the wires. It would be amazing if someone could figure it out, though.

 

Was the air reservoir with the pressure safety valve replaced?
This safety valve is a spring loded valve that opens with overpressure but it can also fail so it opens with lower than the system working pressure. In this case the system will work until the compressor times out or overheats and shuts down.

To hear the leak you need to listen for it when the compressor is still running. When it shuts down air will leak out and stop leaking when low enough pressure is reached.

If your compressor shuts down there must be a code/reason for it. Do you search codes individually in the modules, like in the multicontour seat module?

As it works for 15 minutes I don't think this is wiring or other electrical related. You are losing pressure in the air reservoir and this means you have a leak.

 

 

I've got numerous other projects in the hopper, but I'll take up your suggestions and look more at a later date. No codes, though, other than a meaningless one I can't remember at the moment. Air reservoir is new. Botus is right that these automatically shut off per the OM, but the question is shouldn't it turn back on when cooled down? I would think so, but I guess I can't be sure. And surely no one knows at the dealer, any longer. Our new EQS seats don't seem to time out for seat massage and run indefinitely. My hunch is it is something in the control module. I swapped it with a newer software version, but it needed new coding, and I stopped there, content w/ my one cycle. I'll get back to it later, as I really do like the seats (sorry Botus) and the massage function.

 

Is the pump getting hot? Possibly a thermal cut out. If so possibly a tiny leak in one of the pipes. Get a vaper type person, disconnect pipe from pump and get them to blow vape into the pipe, then have a good sniff around the seats. Hopefully might find the potential leak. This worked on an SL I owned a few years back.

 

I think for many its an air leak - there is no doubt various bits of the seat can
1) play up through lack of use,
2) appear to have other electrical / software bemusement build in,
3) wear out from use,
4) crack pipes for many

I would NEVER use the seat active cornering features - its a weird, far too late to the party to be of any use feature - and of course its just going to wear it all out and give up, thus leaving you stranded without the day to day seat position you need - that said it should never time out

massage I forget is there - but on a long trip or you've hurt your back, to have it working would be a good idea - I thought it ran for longer than the bit of the manual says. more like 15 mins not 8 - and now thinking about it, by the time you have worked out it stopped - in my case seems to be 5 mins - you can just restart it straight away - but you should then expect reduced life expectancy

seat memory - I tend to press it once every few months, and its like it wakes up and says oops I leaked a smidge out - but forgot to top it up, let me put it back where you had it .... but next drive I never think oh the seat feels any different to where I usually have it

shoulder adjustment is a disaster make sure its on nothing ever !

lumbar is all wrong everywhere - so best leave set not to use and make things worse - just add a cheap nasty to look at, but great for support, bit of tat from the pound shop - this instantly resolves all the design flaw in the chairs

 

The massage function, if you refer to that shutting down, does do exactly that. It runs only a certain time, like 20-30 minutes. I never timed it but it always re-starts immediately when I just press the button. If yours just stops and does not re-start immediately it means it probably overheated and was shut down by the system. In my car it did not re-start after it cooled down without re-starting the whole car.

You also said earlier that when the massage stops you cannot adjust any of the seat cushions. The setting jumps back to zero when you try to adjust. I had this exact same issue and I think it is a result of not having enough air pressure in the reservoir.

You have an air leak. Don't spend your time looking after electrical issues. If you had those it would not work at all.

 

Perhaps this is true. All this talk about it makes me want to start investigation it again. It has been smoked numerous times at the dealer (like 6). No air leaks to be found. In a thread mentioned earlier, one member had success replacing the control module...maybe I'll work with BenzNinja and recode my new part and see if that fixes it. I will look for air leaks again, as others have mentioned. Personally, I find the seats incredibly comfortable, and would really like for the whole package to be working.

 

there are LOADS of tests in Xentry where you can see the pressures and if it holds - or indeed if it bothers trying to inflate (electrically)

the actions at times regardless of Arrie's contribution above, is RANDOM electronics - which at time makes it hard to work out what's going on

 

Number uno to check is that air reservoir safety valve. It is a spring-loaded valve and when spring gets weak it will let air out at lower pressure than designed and when you look/listen it you won't hear the leak because it has already leaked out to a point the leak stops. You need to lesten it right after the compressor stops or you may be able to hear it compressor running if leak is big enough. The seat back liner panel must be out in the trunk for this.

 

I took a 4.5 hour road trip yesterday in the CL...right out of the driveway, massage returned to zero and would not start. My entire trip, I'd get one cycle, and need a full shutoff/turn on. I still think it is electronic, as it seems to correlate to no particular condition (heat, length of use, etc), but am looking forward to also investigating Arrie's suggestion. My garage is starting to look like an auto parts store though, so need to get through some other projects first before my wife wanders over to my garage and sees all the parts sitting there.

 

I have NEVER fixed a leak on any seats (only a one off, on a pipe from the pump in the boot - that had a pin***** in it ) and it was NOT the driver of its normal fun...

in 8 years it used to work most of the time as the manual states, and still does - after 18 months of my ownership it started to throw errors (AKA lies) but worked just the same - then I updated the software on both fronts and nothing changed, it worked but sometimes said the drivers one was wrong. But magically could go 6 months between deciding it had any errors or not year after year - I replaced drivers module with later hardware and had it SCN'd to the car, it worked exactly the same - I now think any improvement comes for less noise on the canbus as you remake connections fitting it - and its got nothing to do with replacing a module. Afterwards it was much the same, randomly lying - then one day it decided for 18 months to show no errors.

But quite some time later, the drivers seat went very strange for weeks - teh clue to the issue its noticeable if the radio is off - the pump can be heard to keep running on and off cycling in 2 min intervals - this threw a high temp error for the pump in diagnostics that I have only seen once in 8 years. In the boot, I found it magically had created overnight a visible large pin***** hole on that main pump out-feed. Not sure how that is possible using the pipe work they have ! - fixed that and everything came back to life for a year or so. Then did its usual lies of saying it had issues randomly but worked normally - it often says its wrong but works the same

I have had these episodes where the massage function is just missing - but next drive its all back to normal - in 8 years massage has likely not bothered to do anything on 5 occasions, but I have never sought to fix - it just gets over itself. And adding to its random nature, more than once I've had these episodes where it stops lying about any faults for around 18 months at a time.

Then a few years ago and the back seats started to feel sorry for themselves - I ignored (never checked operation as no one goes in there), but this set of lies persisted reliably for nearly 2 years... in the end played (as documented on another post) and did the Xentry tests - everything was totally dead no switches had any functionality at all both sides - till I got in the back and bounced about in the rears seats in a lively manner - and one by one the rears came back to life and still works now, without errors - only recently realised I could flash the rear seat module with an update 18 months newer - it crashed programming like the baby it is - told it to try again and it got over itself - and now the iPod has worked every time (rather than 75% of the time it wants a fight before it will function !!! )

in my mind its just a fiasco in incompetent engineering....

.

 

Sounds like your leak got much worse and this would go with the reservoir safety pressure valve totally failing. If it has you may be able to hear it without removing the seat back liner in the trunk...but you would need to listen to it right after the pump/compressor starts running. You will hear the compressor and after it shuts down you could hear the leak.

Best to do this is to turn the key ON without starting the car and then pressing your ear against the lower part of the driver side rear seat back.

 

I'll give it a try next weekend. My panel is off anyway, as I was recently dealing with battery issues. Not sure if this makes sense to a S owner, as the CL probably has a slightly different setup.

 

Oh, I did not realize this is a different car, but I doubt the system is any different though. You have the compressor and air reservoir mounted in the rear seat back on the driver side, right?