My MB 2002 C320's battery died a month ago..... Figured all was well.... Of course no such luck.... after three weeks and a trip lasting
four days away from the car the battery was dead again.... my first instinct was electric seat modules which had been replaced back in 2004.
and still don't work very the way they should...

I am now in the same predicament... I am currently 1,500 miles from my home and have visited the "local" MB dealer here a few times.
They really charge through the nose for service and parts.... would it be wise to bring the vehicle to an independent foreign car repair
service? there are many many MB's in this area (so.florida) or should I tough it out until the end of March when I return to my home.

Got any opinions? Dealers truly tick me off!

Thanks

SMS

 

My take on this would be as follows: If your car is out of warranty, which it sounds like it is, then finding a reputable independent is a great option. The key word there being "reputable". Have to do your homework on this one. Besides that, the first thing to do in your case is to have somebody diagnose your battery/charging system and find out the condition of the current battery, alternator, etc. You do know that most auto parts chains like AutoZone, PepBoys, Checker, or whatever stores there are in your area are happy to roll their machine out to your car and do this for FREE, don't you? This is offered as a no-charge service to help them sell parts. Not exact science every time, but if your battery itself has an internal problem, or your alternator is not charging properly, this machine will spot it. If it's seat tracks, obviously, it won't. But you can at least try to eliminate the obvious stuff. Then, hopefully, an independent would be knowledgeable enough to know that. You don't want to pay an independent to snoop around for hours. That's where I'd start. Hope this helps you at least in how to approach it. Battery first, check alternator, etc.

 

I recently dealt with a dying battery (I have 2002 C320 also) and the research available on the web was fantastic. Definitely have your battery and alternator checked first to see if they need to be replaced. My guess is probably not, but I am not a mechanic. If you want to troubleshoot yourself, it will require some patience. When you get in your car, can you hear the fan for the network computer (behind the stereo) still running? The fan in my car would not shut off, so I pulled fuse # 64 and thought that was the issue. However, my battery still died, so next I unplugged the seat controllers. Underneath the front of the seats are three black connectors that will need to be disconnected. The yellow connectors on the passenger side are for the airbags and I'm not sure if they need to be unplugged, but I did anyway. From that point the car did not die even when left for 12-17 hours. I also plugged back in fuse #64 and the network fan would shut down after about 30 seconds and go to sleep. If you can find a good mechanic in your local area, they can then run a diagnostic and see if there is drain even with the seat controllers disconnected. I live in the Portland, OR area and have a mechanic that I can trust with anything, so he determined that there was no other drain (by hooking it up to a huge, expensive machine as mrcoyote notes below) and that the issue was the seat controllers. He called the local MB dealership and the controllers were around $400 each and he was told that even new ones would eventually go bad again. So he did his own investigation (here is where having a mechanic you can trust is key), and found the wire that sends signals back to the network computer and clipped it. Problem solved - saved $800 in parts alone. And there will be no need to fix again in the future. I hope this helps. Ask questions - I've personally pulled every fuse in the car!

 

I also recently experienced exactly same issue, battery drainage and fixed it by replacing the seat modules (invested almost 1k for both). I didn't go through the dealer but invested almost same amount of money for the job. Alternator and battery and sensor, they were all replaced with brandnew ones and then finally mechanic pointed outthe pw seat modules. But now i got realized it can happen again after few years or anytime. humm...

MB300, Thanksfor your perfect advise for fixing the problem. It'sreal knowhow on this issue.What do you mean by clipping the wire?

 

I just took a look under the seats to see what he did, but I don't see any clipped wires. How my mechanic explained it to me is that a diode in the seat controller goes bad so that it continuously sends a signal to the network controller. Somehow he was able to isolate the wire that was sending the signal back to the network controller and that is the one he cut. I'm sorry I'm not knowledgeable with electronics, but if you can get a schematic and find the wire I am talking about, you might be able to do this yourself. I am just thankful that I didn't replace the seat controllers now that it appears even the new ones will eventually go bad. By the way, I still have a buzzing noise in my dome light/sunroof controller when the car is turned off. It doesn't appear to draw any current (hard to believe) as my mechanic tested it out and I've let the car sit for three days without a start, but the noise is there. The only way I can get it to stop is by setting my alarm. So my neighbors and family think I'm crazy when I pull in my garage and set the alarm. Oh well. Other than that the car has been excellent.