Dead Battery Due to Failed Seat Control Module on Mercedes-Benz C320

A dead battery can be caused by a faulty seat control module that does not properly shut down.  Spilling liquids on the front seats can cause these modules to fail.

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Average mileage: 91,668 (150–183,315)
5 model years affected: 2001, 2002, 2003, 2004, more2005
56 people reported this problem
34 people shared problem details
Faulty seat control module. Quick fix published here
Common problem. Dealer wanted $500 for a new seat module. Instead of buying the seat module I bought a $3 "momentary on button" at the auto parts store, cut the ground wire to the seat module and connected the ends to the "momentary on button." Then I mounted the momentary on button on the underside front of the seat. Adjusting the seat became a two-handed affair, holding the momentary on button with one hand while using the other hand to use the adjustment controls, slightly more complicated than original, but saved $500 by not buying the module. The momentary on button connected in this way interrupts the current to the module when it is not in use, that way you won't drain your battery.
Dead battery due to failed seat module to mee too. I have have mercedes roadside come out and replace my battery 3 times, for which I had to purchase one, In a matter of one year. First they unplugged my passenger seat stating that it was draining my battery. The last or third time they replaced my battery they unplugged the drivers seat stated that too was draining my battery. I understand that this may have been a recall and I was never aware of the recall when I purchased this in 2002. Now I and a passenger in my car cannot adjust the seats. It would be good I get an apology from Mercedes and repair this!
Battery Drain. 1.3 amp draw on battery when vehicle is turned off draining battery very quickly. Likely the SCM's not "sleeping". This is ridiculous(fraudulent) considering the frequency and number of reports that these Seat Control Modules haven't been recalled and batterie charged or replaced at Mercedes Benz expense.
i have to unplug my front passenger seat so that the battery will not die. I was told by a mechaninc to just keep the seat unplugged until I am ready to fix it.
Is this the reason why I had to jump start my car everyday? and get 2 new batteries in 3 months and now sitting in my driveway for a month ? Over a seat modules? can someone please tell me how to unplug the seats. I cannot afford thousands of dollars for repair. Thank You
This has caused me unbelievable problems. Where and how do I fix it??
Car would not start and had AAA come in to jump the car. They said it was battery so replaced the battery. Less than a week later the car will not start gain. I see the same issue on for hundreds of folks upto 20 pages of listings...
battery kept dying, replaced battery, problem returned after two days, diagnosed as bad seat module, was told only dealership could fix, this car has cost me a fortune
Mechanic has traced my recurrent dead battery problem to the passenger seat module. It seems more than one owner has had this problem, why hasn't Mercedes Benz issued a recall? They continue to deny this is their problem!
i have same problem with my seat module causing dead battery on both side passenger and driver. I have to leave them unplugged to avoid the high cost repair.
In 2005, I had my car towed due to the fact the alarm would go off due to low battery?? which was ultimately the result of failed seat control module. Cost ~600
Battery dead parking overnight
I have to jump start it every morning. For some reason at night the battery is drained. Checked the alternator and battery and starter everything checked out good.
Slow draw on battery, Mercedes mechanic found the problem, Drivers seat module. R & R $$$ now a year latter the right side passenger seat module went out. We just unplugged it. I understand that its a gasket or insulator that wears out and then shorts out to the frame. Don't know one Mercedes owner who has NOT experienced this problem. The after affects of losing your power is the re setting of the codes $$$$. and a big safety and head hassle
Battery dies overnight, remove seat module connection, now both front seat wont move
Faulty seat control module
The same problem happened to me twice and every time dealer charged me over $1200.not acceptable... Mercedes must fix these issues and recalls this batch. I purchased a brand new C320 and have spend over 10 grand since then for major failures. I thought buying Mercedes gives you piece of mind but it does not!! the quality has gone way down I am determined to not buy another Mercedes and strongly recommend others to investigate thoroughly before selecting on this brand because it only runs up to 100K miles then you have to spend horrendous amount of time and money on it.
battery dies after 3 days of not starting it. It has resulted in two starter relays to blow. I also have the ticking noise behind the dash.
I had the same problem. unplugged both seat modules to stop the drain. A free fix is to take the 12v power line(red wire)at the module plug under seat and cut it and tape off lead coming from harness . Then solder a jumper from the switched power source (ignition)to the cut lead going to multi plug to module. The 12V is for memory for your key unlock seat settings and the seat and steering wheel auto adjustment for ease of getting out of car when you cut the ignition off. Fixed both seats in about 15 min 1 year ago with No issues. The sleep function of the module I suspect is not shutting down with the car off, therefore draining battery
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