When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Apologies in advance if this is in the wrong place I'm new here and don't generally use forums so apologies.
I've had a beautiful 2008 SL350 for almost a year now but something has been annoying me incessantly and that is the lack of lumbar support for both driver and passenger. I bought this car with the plan to do lots of long journeys so working lumbar support is something I really would prefer to have.
Now, everything else works that I believe the PSE pump controls. The door locks work, the soft close boot, the seats move every which way with no issues etc. But both the driver and passenger side lumbar support do not work. When I adjust the switch on either side I also cannot hear anything such as air moving or a pump going, absolutely nothing.
At this point I should probably mention that the previous owner had the common issue where water ingressed into the boot (due to perished boot seals) and the PSE pump broke.
Therefore, I believe that maybe this caused the PSE pump to throw up an error and stop sending air to the seats which perhaps was not cleared on STAR when the new pump was fitted.
I just wanted to ask if my theory makes sense or if anyone else here had any suggestions for things to check or try? I'm afraid I'm not as mechanically minded as I'd like to be but willing to answer any questions anyone has.
If the pump was replaced, it may not have been coded properly. As you probably know, leaks in the bladders are common and will cause the PSE pump to disable the air circuit to the seats. You can reset by pulling the fuse (usually F71), but it will just be disabled again if the leak isn't fixed. If you don't get any air to the seats after a reset, I would have the coding checked.
The OE parts are not really terribly expensive. Left is about $95 and right is around $65 at the online discounters. Multi-contour runs about $240/side for the multi-cavity back and the two side bolsters. If you know how everything comes apart, you can install in around an hour per side. Seats do not need to be removed.
I have exactly the same issue and never got my seat lumber to work. I found 2 cracked airline hoses under both of the seat which you can fix by adding a piece of additional hose pretty easily, however despite resetting the fuse and using my diagnostic, I couldn't get the bladders to work so they are probably gone.
In terms of long journeys, you have a great car for it and is the reason I bought mine. I live in Scotland and work in London so I driver the 400+ miles every week taking about 6-7hrs and the car has been fantastic, getting about 34 mpg too.
P.S. I advise you to do one thing so that you can avoid more water damage to your PSE and remove the little rubber plug under the spare wheel, it is not needed as there is a trim below it so no water will splash in. With the plug removed any leaks will find a way out. The typical areas of the leaks are at the bottom of the rear window seal, you can use SikaFlex 221 sealant to cure it or something that does not set like Gutter Seal.
I have replace the lumbar support in my SLK350 and a SL500. Pretty simple job.... and made much easier if you take the seat out of the car. I disconnected the electrical and air lines with the aide of a "special tool" to hold the seat up. The special tool was 2 x 4 about 10" long. The seat is heavy but comes out pretty easy with the top retracted. The back of the seat and few trim pieces are removed. The old air bag is disconnected slide out the bottom and the new one slide in and reconnected. The entire process took about 1 1/2 hours.... with a coffee break. My local Mercedes dealer had the bladder in a few days. Not sure bladder on an SL350 as far as availability.
Best Regards
Mark
Thank you all so much for the advice and recommendations. I apologise for not responding sooner but work got on top of me and I forgot about this post I made. I tried MikeJ65's suggestions and pulled the fuse, as I did that I could hear the pump reset but even after that the lumbar support did not work. I can hear no air at all on either side so I think it may need to be coded because even if there was a faulty line surely I'd hear some kind of air on either side?
Therefore I may take it to the local dealer for an hours diagnostic and swallow the diagnostic bill. If it needs to be coded I imagine that's a very quick thing they can do but if it's a DIY job then at least I have some certainty and can put the time aside to do it.
Apologies in advance if this is in the wrong place I'm new here and don't generally use forums so apologies.
I've had a beautiful 2008 SL350 for almost a year now but something has been annoying me incessantly and that is the lack of lumbar support for both driver and passenger. I bought this car with the plan to do lots of long journeys so working lumbar support is something I really would prefer to have.
Now, everything else works that I believe the PSE pump controls. The door locks work, the soft close boot, the seats move every which way with no issues etc. But both the driver and passenger side lumbar support do not work. When I adjust the switch on either side I also cannot hear anything such as air moving or a pump going, absolutely nothing.
At this point I should probably mention that the previous owner had the common issue where water ingressed into the boot (due to perished boot seals) and the PSE pump broke.
Therefore, I believe that maybe this caused the PSE pump to throw up an error and stop sending air to the seats which perhaps was not cleared on STAR when the new pump was fitted.
I just wanted to ask if my theory makes sense or if anyone else here had any suggestions for things to check or try? I'm afraid I'm not as mechanically minded as I'd like to be but willing to answer any questions anyone has.
Kind regards and many thanks in advance
Jordan
Hopefully this will help you. First I purchased my car from the USA and brought it in to Canada in 2022 2004 SL600 although this fact is irrelevant it will explain my issue and my fix and perhaps help you with you issue. Second my issues were very similar to yours all my PSE items were working and when I purchased the car both the passenger and driver seat worked flawlessly. My issue, the pulse button would light up but I had not power to either my driver seat or passenger seat and as I read many threads on this site and others I realized there were a few of us that seem to of had the same issue. I looked for leaks and spent some good money trying to chase down the problem. A few months after having the issue I realized the issue started after I had my car in for service and had them reprogram my chip for Canada, KM's and Daytime running lights. I went back to the shop (not MB dealership) and asked if this reprogramming could of caused my seats to stop working. Answer was I don't see how it could have and he did a few things and came to the same conclusion that the pulse lights up but no power and of couse said I should book the car in and they will take a closer look. At this point I let it got. As I do lover the car the joy of driving my 500hp car I decided I would order the Renntech performance chip for the 630HP ( it is awesome by the way!). I installed the software and as immediately tried the seats after the update and guess what, BOTH SEATS WORKED IMMEDIATELY after the chip did it's thing.
In short if everything else is working look for a software issue, it certainly appears to be of been my issue. Hope this helps
08-06-2021, 11:21 AM
