Gobby

Hi all,

I'm new to this forum, I'm a 25 year old Advertising Exec from Auckland, New Zealand. Had a pretty diverse range of cars growing up, and most recently came from an 08 BMW M5, to an 11 C63 (pre facelift)

Loving it so far; the sound, the direct steering, the lack of SMG gearbox... The only pain point I'm having with my black beast, is that the buttons on the side of both my front seats that control lumbar and bolsters don't work.

Now I realise this is a common problem with C63's, and before I get told to use the search fucntion, I have scrolled through every thread in this forum looking for an answer. The problem is pretty much all threads end with "I went to the dealership and now it's fixed". I can't find a definitive solution to this issue that doesn't involve the dealership.

Since both seats are out, I doubt it's mechanisms within the actual seats that are at fault, so can anyone tell me what wiring/modules/ fuses to check? I'm pretty handy with this sort of thing if I know where to look, and I have a friend working in the local Mercedes parts department who can sell me parts at cost, so if anyone can help me solve this issue in a DIY manner, I'd be extremely appreciative.

Cheers,
Raj

JimmyR

I had this very same problem. The driver and passenger seats are on the same fuse so a fault in either seat will take out both. The issue I had was traced to the lumbar/bolster adjustment wiring harness somewhere near one of the hinges to the back rest part of the drivers seat. The wiring insulation had worn away, exposing the wiring and causing a short. So the story goes it really depends on what particular seat setting is used - some positions can cause the wiring to stretch/kink more than others - so not every driver/car will experience the problem.
The fix involved removing the whole seat and pulling it all apart, to identify the wiring harness and then use insulation tape to repair the damaged wiring and to then reroute the wiring harness so it does not kink/stretch.

Gobby

Awesome thanks for the response. Do you by chance know which fuse to check before I disassemble the drivers seat (I don't have a fuse chart in my car, and the only one I can find on the net refers to a generic W204, and has no reference to lumbar or bolsters)?

SaphGreyC63

Check the actual fuse box. If I'm not mistaken there should be a chart in there?

Gobby

I've looked everywhere in my car for a fuse chart to no avail. I suspect it's with the instruction manual...which is with the last owner... If you have one, a picture of it would be super appreciated?

Mort

The fuse chart in my car was in the trunk with the tools to change a tire. That round thing that you unscrew to remove the spare tire with jack and tow bar etc in it. Just a piece of paper so you might have to take it apart a bit as it is tucked in with the tools.

JimmyR

The fuse chart is pretty useless for this. On Aus delivered cars the seat bolster fuse is a 5A fuse if I recall correctly, and it is not specifically listed on the chart. It is located in the rear fuse box ie in that compartment in the boot on drivers side (RHD drive), testing me here but it is about halfway down the column of fuses closest to the front of the car.

Gobby

Yea the car's actually from Australia originally. Did you also have this issue and manage to resolve it? I found the fuse chart buried in the tire well, and located the fuses listed under "lumbar support" (#63 and #64), which were both 30 amp, and intact. I'll have a look at all the 5 amp fuses again though

JimmyR

I just had a look to remind myself. It was either fuse 56 or 59, both 5A, located at the very front of the fusebox in the boot. From memory according to the fuse chart these corresponded to Parktronic or something completely unrelated to seating ie that fuse chart is a waste of time.
Mine kept blowing fuses as quick as I could replace them so clearly it was a short issue, as it was subsequently found to be. I let MB do it, under warranty.

Gobby

Oh sweet thanks, I'll check when I get home. To be honest, at this point I'd just be happy if I could have the controls working long enough for me to adjust the lumbar and bolsters to my liking, not too phased if the fuse blows after 5 mins haha

Gobby

Ok Have double checked all mentioned fuses, cleaned them, and tried puting replacements in. No fuses are broken. Anyone know what to check next?



Really trying to keep going to the dealership as the last resort, because my local one is useless..

Cheer,s
Raj

roadtalontsi

go to the pump, unplug it and plug it back in. It's probably dead but may reset itself and work temporarily.

PoorPossum

I've read a lot of the threads on this issue (I have 2009 C63 w204). As my fuse #56 was good I assumed it was the wiring in one of the seats... However... it was actually the rear SAM unit which was not receiving / sending enough voltage to drive the system. A Mercedes tech is bypassing the SAM unit just to get voltage to the front seats and went via an empty fuse socket so it would still trip if I ever do develop a wiring issue in the seat.

I'll let y'all know if it works!!

PoorPossum

It works! Glad I didn't take my seats apart.

Vladds

Sorry guy, It's the seats wiring.
They start with a two wire connector and 6 inches down they branch it into four then by the seat hinge into 6 and they don't all have room behind the hinge and it scissors away at them.
Essentially, all wires are branches of only two.

It does look like an engineer calculated the resistance of the wiring and decided that this was the most ...... maybe efficient? ..... solution but failed to estimate the impact of the thickness of the wiring.
As an engineer, I respect their work but this is problematic.
So for my passenger seat I went with two triple size gauge wire that I soldered way past the hinge.
Also I came up with an abbreviated version of the work, where a lot less gets removed.
I have two short videos that I put together with the intention to clean them up and upload them, if there's interest.

Cwagon

Would love to see the video.

jas0ndotc0m

Yes Pls

Vladds

I have one more C63 instructional video to edit and then this one is next.

Cwagon

That would be great.
My buttons don't work but no blown fuses.

WillA206

I have the same issue. The window sticker on my car states lumbar support, but the 3 buttons on the side of each seat don’t do anything. I asked my local dealer and they said I don’t have the circular
button the the other side... but why would the window sticker say I have lumber support? (The buttons I have are 3 rectangular buttons on the right side of driver and left side of passenger)

Vladds

Cwagon

Thanks for supplying the video.
Which fuse/s supply the lumbar support modules for each seat?
Also if one seat has pinched wiring and shorts out can this stop the other seat from working?

Vladds

There's one fuse for both seats.
And it's described wrong in the factory diagram.
You have to search the forum, I don't remember the number.
It's in the rear fuse panel, in a vertical stack.

Cwagon

Thanks I'll have a look tomorrow.

ZephyrAMG

Just a point....I dealt with bad seat fuses for one whole day. I kept having my blue fuse pop over and over again. I think I replaced it 13 times.
Do not keep your phone charger plugged into the cig lighter all day and night. They cause the seat fuses and the cig lighter to pop.