Giorgib

Hi everyone.
I have W212 and the front seat stopped moving completely. It moves neither forward nor back, nor up or down.
Does anyone knows what could be a problem?

CaliBenzDriver

Is it both front seats or only driver side?

I would check the ODB2 Faults and Fuse for good measure then the seat module may need closer attention... (inspect each pin of its PCB connectors)

Giorgib

The problem is only on the seat on driver's side.
I checked the fuse and electricity doesn't get into the fuse at all.

CaliBenzDriver

good deal, that is pretty big troubleshooting step done!
You now know the problem has to do with fuse supply and not down into the module.

Next step would be probing that circuit with a diagram to find where your break is located.

abkeek

I had this problem in my driver seat around the second year of owning the car

the problem was that the factory motor went bad, replaced it with an aftermarket motor (cant remember the brand) around 4 years back, i still get codes for the aftermarket motor but its working fine.

Left Coast Geek

you used a volt meter to check one side of the fuse against a good chassis ground, right?

is this a US model W212? which year and version 212, and are the seats the standard ones or one of the fancier optional seats, and do they have memory or not?

oh boy, looking at the block diagram... seat adjustment controls in the left front door speaks over LIN bus B5 to the left door control unit N69/1, this in turn talks over CAN B to N32/1, the Driver Seat Control Unit. This control unit in turn connects to all the motors on the left seat. LIN is a low speed bus used where CAN bus would be overkill. CAN bus B is the interior CAN bus.

N32/1 gets its power from Fuse F62 in the rear SAM. The various motors are directly connected to N32/1

The right seat is the same but the modules are N69/2, N32/2, LIN bus B6, and fuse F64...

does everything else on the left door work, like the window, mirror? they are all on the same N32/1 left seat module.... if they rest of the door stuff all works, the seat issue is probably with N32/1 or the F62 circuit

Left Coast Geek

hokay. I finally figured out how to PDF stuff from my isolated VM running WIS

first is a block diagram, second is the detailed diagram of the driver seat N32/1 and motors and stuff. I didn't bother with the detailed diagram of the door controls.


oops, gotta rotate the PDFs 90 degrees clockwise, fire the printer.

konigstiger

You do not provide model year, model, and location. USA trunk fuse panel: passenger seat adjustment switch f44 (30A), driver seat f45; seat CU f62 (25A), f64; and F relay only for vehicles without code 275 (memory package). All fine, have someone pull codes worst case scenario could be SAM.

mentiote

Sorry to hijack and resurrect this old thread. I'm running into a similar issue with my US 2010 E350 4MATIC (w/ memory seats).

• Driver seat adjustments (including lumbar) do not work
• Driver seat and mirror memory settings do not work
• Mirror controls works
• Other door functions (windows, locks) work
• Steering column adjustment works
• Passenger seat adjustments and memory settings work

f2, f45 and f62 fuses visually look okay, though honestly I don't work on my car often so I'm not 100% confident.

I brought to local garage to take a look, but they only said "driver door - no communication to switch panel from module" so their scanner could not determine if it's the switch or the seat control module. Additionally they said it was a "dealer only repair" since "it would need to be programmed".

Would appreciate any insight / advice from the community. Thank you for your time!

CaliBenzDriver

Good job on doing your homework to know what you are dealing with. So you've pretty much ruled out fuses for now.

DTC: "driver door - no communication to switch panel from module".
Based on the above code info, I would have a bias to look at the door module before suspecting the button or seat modules.

The simple buttons... are not garden variety! They are classy Benz buttons organized around a fancy microcontroller to stream data over a LIN bus (I've had no exposure to these door buttons but central console).
Door / Seat modules:
luckily it's easy to work on both of these modules. They are cleverly installed for quick removal with couple snaps. No need to remove door panel or seat rails.

MY'2010 may or may not use solderless pins such as with post-facelift models. It'll look obvious once opened up.

You can try to gently tap around these modules to see if indeed you're dealing with oxidized connections. Less likely broken wires within the door harness.

At the end of the day, I'd say deal with all of it while you're in there... I've fixed both my driver door/seat modules then same on passenger side... ✅

Left Coast Geek

most certainly, check the wiring to that door module. it communicates with the chassis over a low speed bus, I forget the name but its not a CANbus.