jhartmac

Ok have had this C320 for about a year no problems then all the sudden I get a message something to the effect light sensor problem visit workshop, well after waking up with a dead battery I considered the sensor that turns on your lights automatically when it becomes dusk out, so I used the headlights with the manual switch- no more problems...........started using the sensor again worked for 3months, then dead battery, used manual lights, still a problem, battery keeps draining, full drain occurs in about 6hrs, hooked up a multimeter to the battery and it looses voltage slowly with the car turned off, with the car running I get 14.4volts which means the altenator is ok, but............every nite I wake up with a dead battery- any suggestions???

white_w203

could be an alternator or just new new positive cable to the battery.

mleskovar

There are several threads that talk about battery drain. Seat module is a big failure item for this symptom. But you're on the right track....keep disconnecting systems until the drain stops.

KIRA

+1 HAPPENED TO ME RIGHT NOW!!!

DEALER ASK ME TO PAY FOR REPAIR!!

my car is 02 and is out of warranty...

cost total $1k for these **** to replace....

do u guys think i could talk to benz said is their fault?? and get free of charge?

rtking

I paid $500+ at the dealer to have them diagnose the problem. After 3 days, they said that there was not problem! WTF? If I leave the car for a week, the battery is drained. I have no idea what's causing the drain...

Bob

coin

I experienced the same problem (jumpstart the battery two times in 1 day) and the dealership performed "current draw test". They found that my right front ESA module was causing the battery draw. They disconnect ESA and ordered the new part from Germany.

I hope this helps !

raklert

Most likely you might have leakage from your seat module. This is common problem for late model benz. Its a shame but this is why people are starting to question Benz' electronic reliability. I got mine replace after replacing 2 batteries and they said I had to replaced both left and right module cost me almost $1000

BKLYN_C

Get an AMP meter and one by one disconnect all the systems (unplug fuses). In the matter of 5-10 mins you will know the place of drain. Volt meter is wrong tool for this.

usc240

Mine had problem with front seat module. I just unplugged the front seat cables...no more battery drainage problem.

TruTaing

Im kinda confused about this... You unplug the fuse, then you use the amp meter to see if there is still acurrent running through it. If there is, than thats the system draining your battery?

Please clarify?

-j0hn

jhartmac

I believe it sounds like it s class action law suit time, if Mercedes wont do recalls then we all get together and FILE, if interested send me your information, believe me I will get the ball rolling, on top of this issue is the other one......................how many have had ball joint replacements on late models? expecially 2001's?

mleskovar

Do you mean front bushings? Count me in on the bushings. Even though the seat module/battery drain problem is well known I don't think it's prevalent enough to do a class action on. If you're that interested in doing a class action go after the MB SBC brake backup sytem and do us all a favor. You might even save your own life.

jhartmac

Ok I went out and disconnected the seats, the front side plug ins? I guess on the back is the motor plug, anyhow after disconnecting them..........nothing the "low hum" was still happening, and in addition the airbag system was also off, tried waiting 10-15mins with it disconnected then reconnected ................nothing so Im at a loss, did someone say EAS system? can you elaborate on that one please.

mleskovar

[QUOTE=jhartmac;2016055]...nothing the "low hum" was still QUOTE]

If you're talking about the low hum noise coming from the overhead console....that is normal. There's a fan in there that runs for a while even after the key is removed.

aborwick

I had the same problem with mu 2002 C320; it was the seat module draining the battery when the car was parked. This seems to be a common problem.

s1mple

hi, thank god i found this post. i recently found out what was draining my car over night, the seats. i unplugged all the seat fuses and it stopped draining. i thought it was my car stereo i just got put in. but i'm dead serious its the seats cuz after i unhooked the seat fuses, radio fuse still in it does not die after letting it sit for two days. i was wondering how much does the stealership charge for a repair like this, or has the seats been recalled? thanks let me know. been having the problem for months and would really like to start driving my car w/o the fear of battery problems again. thanks

jhartmac

Ummm..........ok since the fuse box does not have a schematic on it how do you find which ones control the seats.............or did you unplug it directly at the plug in buss bar under the seat? Can someone break this down for me, I know I can be a little slow lol

jhartmac

Ok it worked!!!!!!!!! I disconnected I guess the correct power plug vs the control plug, but anyway no more dead battery, thats a relief, now the question is, for those of you who have had this issue, is it isolated to one seat or both? and can I purchase the part myself from MB? if so can you reference the part # and name please?

Racin_fool

you should be able to purchase them from MB whenever you need to.

The most common ones I have seen fail are the passenger seat control modules. I am not saying that the driver's seat control module does not also fail, but the more common one is the passenger seat. Also on the earlier W203 cars I have seen the overhead control panels cause a battery drain (Dome Lamp Assembly) As for the part numbers for the seat control modules, they may vary from model to model.

jhartmac

Thank you for the info I called MB today they said depending on the VIN# that would designate what seat control module would fit however he said they average about #189.00 ea................well I will be replacing those myself needless to say.

Racin_fool

You may need to unbolt the seat to get them out and back in, but I have done them before with the seats bolted down. Just expect to scratch up your hands some.

jhartmac

Cool thank you, I will try it first with the seats still installed

jhartmac

Wow update after 2days of no dead battery guess what its back again!!!! and believe me its not the battery, in fact its a new battery, I tested it by disconnecting the negative terminal overnight, after reconnecting in the morning no problems.....strong battery, now not sure WTH to do.

TruTaing

Note: It took my seat module a full 24 hours of no driving/starting the car to fully affect my car's ability to start up.

coin

I recall this -- my dealer always returns my serviced car on the day itself. However, on the day they changed my control unit, my car had to stay overnight. It might be due to the same reason as TruTaining has mentioned.

The part # 211-870-47-26 is for the RF seat control module.