CatalystW203

The initial battery was observed to be running down, so a new 100AH battery was used to replace the MB battery which the electrician reported dead. But, even with the new battery, if the car is not used extensively within 24 hours, there's a possibility that the next day it wouldn't start & the check engine light is up presently. It's suspected that something's draining the battery, any idea what it could be please?

350SL

Try disconnecting the negative terminal and check for an ark. Could have an open diode in the Alternator bleeding back. Or a power draw from an accessory like an aftermarket amp etc. Dave

CatalystW203

Thanks Dave. How do I check for an ark please?

As regards aftermarket, didn't get it brand new, but the only change has been the condenser which was observed to be leaking after a jam by some driver. I guess the issue was observed sometime after that change. Like I stated earlier, the battery was also replaced.

Prior to the battery change, the check engine light was on and sometimes on starting the car in the morning, there's some stuttering sound which dies down after the engine runs for a little while. From scanning, it read P0301, a later scan read P0301 & P0302. On connecting the new battery, the drive was smooth & the response was very much improved and the early morning stuttering was gone. The check engine light was cleared and didn't return until now.

Any further hint would be appreciated.

MJ50

moved to W203 forum...

optimusprime m1

They will arc anyway .Anything conected to the battery , clock, computer, alarm, all come alive when puting battery leads back on .Also the arc, or spark, from the battery leads can cause explosion . Bad idea.. Do you lock the car after use in the grage ? This will shut down the computers and save the battery . Other battery drain is alternator regulator .Some are replacable items .Do you see a no charge on the dash information .

tjts1

What year? What mode? Its most likely the power seats.

CatalystW203

Model: C180
Year: 2001
Engine: M111.951

@tjts1, if it's the power seats, how is it to be fixed?

CatalystW203

@Optimusprimem1, there's no "NO CHARGE" on the dashboard, took the car for a test and everything checked out fine, alternator & battery, I've also got a small tester which I used earlier & result was positive.

CatalystW203

Battery Test Result

optimusprime m1

Do you park in a garage at night ? you never said . And do you lock the car up at night .

tjts1

Disconnect the plugs underneath the seats and see if the drain goes away. If it does, do this.
http://www.benzworld.org/forums/w203...ower-seat.html

Gramma_Benz

https://mbworld.org/forums/c-class-w203/262131-temjinx2-s-20-seat-control-battery-drain-fix.html

CatalystW203

@Optimusprimem1, the car is parked just outside the front door, not in a garage & it's locked at night.

CatalystW203

Thanks guys, I don't have the car around always but my wife does everyday .... I'd be around & would have this looked at over the weekend & give a feedback afterwards.
Note: The power seat on the driver's side ain't functional at the moment, but the passenger's side is fine ....

optimusprime m1

This may end up with the SAM unit fault ..

CatalystW203

Please, what is this called? And what are the functions? If it is faulty, what symptoms would be observed?

optimusprime m1

I dont know what the part is other might so keep looking in wont you. I can see its nothing only a connector block .

playfair

try to measure drawn current when car is locked. acceptable values are in the 50-60 mA range if i recall correctly. also IF you have an alarm remember some of them kick in fully after 2-3 mins. if current is too high try pulling fuses one by one and see if there are any changes

CatalystW203

My head's popping on this, almost .... I actually got a replacement SAM, not brand new though, couldn't get the wiper hook off (my bad) to swap it myself, so I decided to take it to a workshop to have it changed. So we decide to let the guy in the workshop run his diagnosis first & he says, "there's a short on your rear brake light" I knew that the rear brake light, left, was out, it was indicating on the dashboard already but that wouldn't be the reason the battery would drain, he looked through his scan tool again & mentions CAN bus, I then explained to him further the experience we've had & also that I had a replacement for the SAM, he says "your SAM is fine", I insisted show me what's wrong & he tells me, "you ain't a pro, let me do my job" after a series of discussions, he has the rug on the driver's side loosened, exposes that connector & says that's the bad guy .... He's yet to replace it but I'm trying to ensure the right thing is done .... That's why I need to know if this connector can cause a battery drain anyhow ....

playfair

well, in my w203 (which is European market, year 2002, M271) brake lights are powered via no 62 fuse, 5A, but i'm not sure whether yours is the same. the photo of the connector is out of focus and i can't see much but check for "burns" i.e. charcoal like areas that can cause a short. if that's the case and your brake lights are powered via CANBUS the guy in the workshop might be on to something. inside the dashboard as you open the driver's door you should find a "fuse chart". see if your brake lights are supplied by a fuse or "electronic" i.e. CANBUS. But why don't you let the guy replace the "culprit"? if the problem is still there it's on him to look further

CatalystW203

@Playfair, yea, I've given him to go ahead to have it replaced, I'm hopeful he's spot on, I've seen the fuse chart also .... Thanks