TemjinX2

Hi Everyone,

I just bought a c32 from the dealership. Unfortunately i'm having the famous battery drain from the seat control modules. The dealership saids that only cover drivetrain not electrics in there limited warranty.

Anyways, i've been reading the past threads about this issued and dont really feel like paying $300 a module.

I found a couple of used modules on ebay from the w203 chassis for cheap.

Does anyone know if the other w203 seat control modules would be compatible with the c32? I know the part numbers are different but they look the same.

I would imagine mercedes would use the same part for all there w203 models to save money.

Al Bundy

I would think that they're the same, but I can give you the part numbers when I get my car back in the next few days for the same problem.

Just FYI, there's a third module that goes bad as well, it's located in the cluster with the dome light/SOS button, and it controls the sunroof. My service advisor said that all three usually fail around the same time, so you might want to replace that as well.

And I would STRONGLY suggest getting an extended warranty that covers the electrical system. The cost for replacing these three modules alone is $1900. I paid $2300 for a 4-year bumper-to-bumper that will pay for itself with this one repair. Lots of warranty companies won't cover AMG's, but I'm positive this one does:

http://www.prizm.net/index.html

TemjinX2

thanks for the info. Yeah i'm thinking of getting it after i get my tax refund. I just can't believe a 02 mercedes is giving more electrical trouble then a 14yr old integra.


Damn german electrics.

I'm gonna recharge the battery tonight and disconnect the modules and see if there the problem. if it is, i might just experiment. I found of couple of them for $80 on ebay for both.

SUNILP

they are the same.

TemjinX2

perfect... i have two on the way for $100 shipped

dkflipse

Damn. I just paid over $300 for these. Keep in mind if these are the "old" ones they will fail again. The "new" ones do not have the fault - at least that's what my SA and board members have said. Keep up updated as this is a common problem.

TopGun32

did you search by the part number?

what guarantee do you have these are not defected?

we need to find a way to diagnose if they are faulty or not...

TemjinX2

The part numbers were different since there for a regular c-class model. But doesn't mean there different parts. Mercedes might of just given them different part numbers because there for different model cars even though its the same part, so they can charge more for the upper models.

I have no guarantee other then what the seller said and my paypal fraud protection since i bought them on ebay.

For a chance to have working modules for $50 each instead of the $200 a piece i figured it would be worth the risk.

There is a theory in the c-class forum that the reason it drains the battery is because the circuit in the module that tells the ecu to turn power off the seat after 30min becomes defective and never tells the ecu to turn off the power.

If its electronic like that..there's no real way to fix the problem...hence the dealer recommendation is a replacement rather then rebuild.

If someone would put up a schematic of the seat harness...i probably could've fixed the problem for $20.

I didn't feel like getting a volt meter and testing every single wire...so i went with this option.

TemjinX2

i'll probably install it next week...i'll try to keep everyone updated.

I dont get the germans....nothing should be live when the car is off other then the ecu and clock.

TopGun32

wish you successs.. we all need this..

can you take some pics for us and share

we love to save money around here and specially avoiding the dealer.

AWDman

maybe it's a defective relay. i had one go on my ferrari's fuel pump circuit replaced it with aftermarket $5 rather than dealer $80.

if it's a chip i wouldnt know how to test it but finding replacements once it was identified should be a piece of cake. (the whole unit will be assembled from common electornic parts).


i'll see if i can get my module pulled and opened up. i have to say i'm distracted by the m3, reading up stuff on the "dark side" forums...

TemjinX2

just to give a update. After not driving my car for another 2days, the battery died. I thought it might be the rear fuse box so i took it into House Of Imports to get it diagnosed.

They charged me $200.00 to confirm that i was the seat modules. They confirmed both modules were dead and were going to charge me $800 to install. I said no thank you.

On top of that my advisor was kind of a jerk on the phone and i had to wait 45min to pick up my car, when they said it would be ready in 5min.



I have a premium brand car and pay premium prices to get such crappy service. The other House of Import threads are right...there service sucks. I get treated better when i take in my camry to the toyota dealership.

ANyways....i just got my modules in the mail today. I'll probably install them this weekend. I'll try to take pics.

c32used

Welcome to MB!
Toyota/Lexus will treat you way better.

TemjinX2

i think its just lack of competition. There's only around 3 or 4 mercedes dealerships in my area..where as there around 10-12 toyota lexus dealerships.

The toyota guys knows i can go down the street to the next toyota dealership. The mercedes guys know that i have to drive 20-30miles to get to the next one.

c32used

True but a bad experience will make that additional 20 mile ride seemlike nothing...

TemjinX2

i got off work a little early today so i decided to replace the modules.

It confirmed that the w203 modules will work for the c32.

I got mine off a c320 w203 for $100 shipped off ebay.

I promised pics so here they are.

There's two ways of doing this..the careful way or the down and dirty quick way. Its up to you which way you decide.

I go over the careful way first.

Tools Needed




Before you unplug the harness. Make sure you have the seat as far back and as high as possible. This will give you some room to work. Unplug the front harness once you set the seat in position.

There's a silver tray that holds the seat module in place under the seat.

Use your racket and the correct torex end to underscrew the black torex screw holding the silver tray to the seat.

There screws on each end of the seat.



Once the screws are off, unplug the harness in the rear and front of the seat modules.

There should be two black plastic rails holding the seat module to the harness in the back. If you grab onto both the plastic rails and push the seat module upwards, it should hook the modules from the plastic tabs.

Now slide out the seat module. Here's a comparison of my old module and the one i got off of ebay.




As you can see there exactly the same.

Here's a closer look.





As you can see the part numbers are exactly the same.

Install the new seat module.

Plug in the rear harness first.

The module is marked to tell you which harness goes into which socket. In case you forget. Starting from left to right it goes Orange, brown, black then green.


Plug in the orange one last since its the easiest to put in.

Once the rear harness is in, plug the front ones back and test to make sure the module works.

once you test it..unplug the front harness and slide the module back over the black rails and hook them back.

Then put the sliver tray back and do the reverse of my previous steps and your done.


This took me around 30min to do. Mostly because i didn't know what i was doing and some of the other threads said i needed to take off the seat. I didn't want to do that, so i figured out a way without taking out the seat.

If i knew what i was doing from the start it would probably take about 15min.


The stealership said it would cost $800 for both modules installed.

I did it for $100..now I can use that money to buy a lcd tv or mods.

TemjinX2

Here's the direction for the quick and dirty way.

No tools needed. Can be done in 5min.

First move the seat as far back and high as possible.

Unplug the front and hear harness.

Then push the black tabs from the seat module away from the silver tray.

Then push the seat module upwards and release them from the black plastic rails.

Take out the seat module and swap it out for the new one.

Plug the rear harness in. Then put if over the black rails and then push it back onto the silver tray.

Connect the front harness and your done.

TemjinX2

Take a closer look at the seat modules. It looks like the new revisions do have different part numbers. It looks like the previous owner did replace the driver module already.

Based on the date stamp of the module, it looks like it was replaced

4-11-07.

Here's a pic. Keep in mind, the international way of stating the date is day then month then year.

Its funny how the stealership said this one was dead too considering it was replaced only a couple of months ago. Another way of trying to get $400 out of me.





If you study the picture.the new revision does have a different part number.

I'm assuming my passager module was the one that went bad.

I probably going to keep the driver module as a back up for now.

splinter

Excellent posts. Thank you.

dkflipse

Great post - even if it's too late for me

Moviela

California presumes a one year warranty on any electrical part. You might ask Mercedes to replace that 07 module.

Nice write up.

I know now why I did not need memory seats.

c32used

Great write up and thanks

TemjinX2

i dont think the 07 module is defective. I think the dealership just said it was, to get more money out of me. I believe my original passenager side one was the one draining the battery.

TemjinX2

i'm glad i was able to contribute as a new member.

I wished more people did Diy's on the forums.

It would definately help mercedes newbies like me.

calimax

Thanks for the write up I hope to never do this, but if I do, I know I've had your help doing it. thanks!