Just a quick thought: you could disconnect the lumbar support vacuum pipes at the pse pump and blow into them, to see if they hold pressure. Or use a vacuum pump, if it doesn't hold vacuum it doesn't hold air is my reasoning. That way you know if you got a leak.

I checked alldatadiy.com for diagrams for the lumbarsupport system, this is all they had (see attached):

A37, A37/1 PSE control module
4 Orthopedic seat backrest reservoir
19 Pressure control
20 Lumbar support backrest

Notice that there is a reservoir for the orthopedic seat bladders. There is a test proceedure, described on alldatadiy, but I don't know if it's gonna be helpful to you.

 

As a note: the air reservoir is not located right next to the pump, as would be a normal, simple engineering location, but instead, one grey hose runs behind the rear seats, curls around the wiring harness, behind the sound panels, and is firmly mounted between the rear fuse box and the fuel lid vacuum locking mechanism (under the red manual release, should the vacuum locking system malfunction, that red manual release is a life saver!)

The test procedure is practically worthless, so I recommend for 1996-99 (from personal experience):

1) disconnect the P+ grey line and pressurize to see if there is a leak in the pump.

2)on the multi connector, The two side by side hoses are for the seats, the single one further apart is the reservoir. I would test each by cutting the lines and after finding the leaking one, use a rubber splicing hose to reconnect (not pretty, but works just fine, especially on a older car where the hoses will NEVER come off the connectors!)

3) go to the leaking part, and fix there (seat or reservoir)

UGH! Stupid German over-engineering! It could have been SO simple!http://www.benzworld.org/forums/images/icons/icon1.gif

 

Oh and btw, the vacuum lines for the lumbar support system are 3 gray lines; two for the bladders and one for the reservoir in the trunk.

Refer to this old post:
http://www.benzworld.org/forums/w140-s-class/1288970-picture-pse-please.html

Hope this helps.

 

This was my problem ,see the crack in the lumbar support (arrow), both sides had the same fault that shut down the lumbar support air supply but upon installing 2 new bladders the problem is fixed ,only problem changing them i had was on the 1st seat, i didnt tape up the airhose like shown in the picture to feed it through the channel under the seat ,total cost 50 $ each from MB Germany , Paul has all the details for that .
You cant patch those bladders because when you take it out it will disintegrate on its own in a way,i already try'd that ,lol.

 

Replacement of Air Cushion For Multi-Contour Backrest on the Driver's or Front Passenger Backrest

Preliminary work :
Cover on driver's backrest removed, refer to "Replacement of Cover on Driver's Seat Backrest". See: Seat Cover\Service and Repair

Vacuum lines on triple rubber distributor (1)
detach.
Reinforcement plate (11)
unhook from backrest frame (10) at top and bottom (arrows).
Reinforcement plate (11)
remove together with the air cushion. When installing, ensure correct line routing
Reinstall in opposite order.

Backrest:
Driver's seat backrest
place on a suitable base.
Screws (arrows)
screw out.
Rear panel of backrest (1)
remove.
Cloth apron
unhook and remove.
Adjusting wheel (3) and lower surround (4)
detach. Observe installation note!
Panelling (5)
remove.
Panelling (6)
remove and pull out lead (7) on panelling (6).
Cover (8)
detach all round.
Additional lower cloth loosening
remove from the plug-in fold.
Transverse loosening device (9)
detach at the top and remove.
Backrest frame (10)
remove from rubberized hair support (16).
Plastic hooks (13) on transverse and longitudinal loosening device
unhook.
Lateral nettle strips
detach.
Plastic ring (14) on inner head restraint eye (15)
separate and remove.
Head restaint eyes (15)
remove.
Cover (8)
remove from rubberized hair mat (16).
Reinstall
in reverse order.

Installation note
Adjusting wheel (3) must be replaced after each disassembly.

 

And some more:

 

Unfortunately I don't have the part number for the bladders.

I've just dumped all the photos of the bladder and removal of the seat backrest, in here. Hope it makes some sence.

 

Great stuff


Paul,
Thanks very much. It will be great to have this on the site for everyone. I did not suspect removing the bladders was so involved. The directions say "Adjusting wheel (3) must be replaced after each disassembly." It looks like the adjusting wheel is part of the seat. Is that really the case (its hard to understand given my lack of experience).

I am assuming the adjusting wheel (3) is not the lumbar adjustment control (pressure control in the first diagram) though one might thing that based on its name.

If the pressure control is on zero for a seat does that mean the bladder is isolated? Is this equivalent of removing the line here and plugging it? If this were the case, one could set the control to zero and see if the problem goes away or is isolated (never thought of this until now). If I could set the passenger control to zero and gain full functionality of driver side I would do that in a heartbeat, plus it narrows down where the problem resides.

I presume there are no cheap bladders, just the dealer. Sounds like my plan of recovering a good one from one of the vehicles may be challenging given the bladder's age and expected fragility, not to mention the trouble of getting it out.

Where does the secondary bladder (passenger side) split off from the vacuum coming to the driver's seat?

Regards,

Meles

 

I think you might be onto something by putting the pressure adjuster down to 0 on either side and try diagnosing it from there.

The passenger side bladder, gets it's pressure from a separate line directly from the PSE pump. That's why there are 3 gray hoses for lumbar support; 2 for each of the front seats, and one going to the pressure reservoir. Or well.. that's what I assume.

This is the part number for the bladders: 000 970 06 90 Can't find a cheap replacement for you though But seeing as how they're only 50 bucks from the dealer, I'm assuming you're gonna be alright.

 

I think its a good approach to test the lines with a simple hand pump;

http://www.benzworld.org/forums/w14...g/forums/w140-s-class/1260773-help-diagnosing-lumbar-support-2.html#post1883963

br,
syljua

 

Good link


I'd missed that in my review somehow... "to answer your question, yes, the sypply line is always under pressure, think of the system like the following:

-water pipe from the outside, to your bathroom
-faucett
-bottle, or a ballon getting filled with water

respectevly:

-air supply line (pressure is always there)
-knob
-air pillows in the seat

once you fill the ballon with water and close the valve, the ballon will be inflated and the valve would not allow the water to leave the ballon (assuming the ballon is still attached to the faucett)

now even if your water gets shutdown from the water company, or even someone hack saws the pipe outside your house, the ballon will maintain its pressure.

the only way to deflate the ballon is you release the water at the ballon's neck, and let it drain in the tub, thats how the release mechanism works at the knob, and thats why you get the hissing noise when deflating the pillows, because the valve dumps to the outside. "

I'll play with it some. Both cars have occaisionally fired up the lumbar systems after not working for some time. I am presuming this is from fuse or battery disconnect. I just did fuse and will check that when I drive the car. I hope I don't have to go to the dealer to set the PSE. I've got a blinker that can clear the codes in the computer and I'll try that if necessary.

I've got a little hand pump from my vegoil kit (not on this car yet) that I might be able to hook up with another hose and manually pump up the bladder (don't want vegoil in the lines!)

 

When I am fixing seats in the 230 I use a little air brush compressor with a 1 way valve from a hand bathroom/ kitchen spray. You can get plastic tube dirt cheap from any shop that sells indoor fish

 

Redux, I am done!

Thanks for everyone's help. What follows are my diagnosis suggestions and then what I found with my two cars (an example). I am not putting this in the knowledge base since it has not detail on the actual repair. The following may allow the owner to regain function of one seat without doing any repairs.

1. You are reading this thread since your lumbar is not functioning. You turn the dials on the seat and either nothing happens or you feel the seat losing air. Your PSE pump under the rear seat operates the door locks, lumbar, and a few other things. If your lumbars are leaking the pse will eventually shutdown that part of its circuit and then nothing will happen when you operate the dials.

2. To further diagnose this system you must get the PSE pump to start up again. Try pulling fuse 11 for 30 seconds, disconnecting the battery for 10 minutes, and/or clearing the codes out of the computer. This is a debated area, so later or all models may require clearing of codes ($20 DIY code blinker can do this). Try fuse 11 first.

3. Set both seat dials on zero (don't over turn past zero). With the car in a quiet area, turn ignition fully on so indicator lights come on. You can lock and unlock the doors so you can hear the pump under the seat. Determine if there are any leaks between the dials and the pump. If everything is quiet after a while with no pump noises then you don't have a leak between the pump and the dials. If it keeps running try to track down the leak quickly by listening with your ear around the floor areas of the car. Start listening near the dials (which could be bad.) If around the dials is leaking, you'll need to pull off the covering (not detailed here) to determine if the leak is the dial or a connection to the dial.
Note: Once the pump start running continuously, move quickly to diagnose and then turn off at the ignition. You don’t want the PSE to shutdown the lumbar line again.

4. If no leaks so far, now sit in one of the seats and put the dial up to a higher setting. If you did the prior steps correctly (step 2), you should now here the pump activate and feel it fill the bladder. With luck it will fill up and stop and that circuit will be fine. If the pump keeps running you have a leak. Quickly get out of the seat and listen at the lumbar area and the dial to determine the leaks location. It could be the bladder itself or likely the dial.

5. Once you've tested one seat, sets its dial to zero and repeat the procedure on the other seat. If just one seat is leaking you may wish to leave its dial on zero and allow the rest of the system to operate. The bladders are $180 at the dealer (Mercedes varies prices up and down, so check).

That is as far as I go with this is diagnosis as I've not had to repair my cars.

Examples:
My white car had no leaks with the dials on zero. Passenger seat leaked from the bladder when dialed up. Driver's seated was tested next and it leaked from the around the dial. I had swapped dials between the seats before and the driver's seat had leaked on its own indicating a bad bladder too.

My black car's driver's lumbar worked perfectly. Passenger seat leaks from the bladder. I will be keeping the passenger dial on 0 since that will allow the driver's side to still work. My passenger bladder leaks in my white car so I will not salvage it for my black one (white going to junk yard soon).

Further note:
(Pure conjecture on why the lumbar units fail.) I don't believe the previous owner used the feature much and I've run into three cars with leaking bladders on the passenger side. I believe not using the feature may hurt the bladder. It may crack more easily when fully deflated. I would keep all seats on 1 so that they are kept under modest pressure. (This is counterintuitive as you would think keeping them deflated would take the strain off.)

 

2. To further diagnose this system you must get the PSE pump to start up again. Try pulling fuse 11 for 30 seconds, disconnecting the battery for 10 minutes, and/or clearing the codes out of the computer. This is a debated area, so later or all models may require clearing of codes ($20 DIY code blinker can do this). Try fuse 11 first.

Do also check that the Variant Coding of the PSE tells it that the car has Multicontour
Seats. Its done in HHT;

(I still believe that a PSE with a faulty lumbar, will revert to setting the variant
coding to "no", but I do not have proof...)

br,
syljua

 

Cost is $42 US each for the Bladders (kidney shaped ) ,shop around ,here in Sydney they cost $150 each from the dealers .
Prices vary from MB shop to another i noticed ,just for the oilpan gasket they ask't me 180AU$ ,i found it for 30$ instead (just an example ) .
Notice the colour of the old bladders,the bladders are transparent white when new ,also the white backpart of the bladders is not needed when you slide in the new one as that would involve to much of the seats inside removal .
The connector pipe from the bladders might be different for some models (like mine ) but it comes out while holding it under hot water and connect your original plug,not a problem there. :thumbsup:
I'm not to sure if i can add the MB Dealer with the cheap prices here ,i need to ask a specific person 1st ,Send me a PM for Details if you need .:thumbsup:

 

2008 s class w221 lunber support both seats not working pump and fuses ok suspect pse valve cant find it can need body help

 

Frier

You've planted your question in the wrong garden. This is the W140 S Class forum. Not certain if your PSE pump is under the passenger (right rear)/seat cushion or not.

You'll obviously get better traction in the correct forum.

Jayare