Hello, I'm the owner of a 2001 C320...

I hope somebody out there likes mysteries because I have a bit of a "who's done it?" Ok maybe more of a "who's doing it?" See, something is completely draining my battery. Any ideas? Here's the clues I have so far...

According to a mechanic, it's not the battery, and it's not the alternator. These were tested previously when this problem first reared it's ugly head.

Here's a curve... the mechanic found that it was a relay under the driver's seat that was sticking! (A $400 relay, that controlled the driver seat and airbag.) Anyway, we unplugged it and the battery was fine. Now the problem has returned. So of course I've tried unplugging the passenger side relay, also found under the front seat... My battery is still being drained.

Again I ask, any ideas?

Thank you very much.

 

its your seat control modules, one of the two or both. theyre called esa- driver and esa-passenger. they cause draws. if you have an amp meter, have that on your battery cable and unplug one of your esa's (under the seat, black box with 2 connectors in front), see if your draw goes down, relpace that one. or just leave it unplugged and you wont be able to move your seat.theyre expensive though. good luck!

 

I own a 2002 C320. Same thing. Both seat control modules were draining. Took it to a generic garageand the replaced my battery. A week later car is dead again. They had thrown away my old batter. So I am stuck with a battery I did not need. Took car to Benz they diagnosed the modules. $1700 bucks plus $200 for batterylater. Car is fine. [:@]

Lesson learned. Only deal with MB garages.