PLEASE HELP ME THE F*** OUT! Battery drains over night or long parked.. and having to keep unplugging my battery n plugging it back in to drive everyday. Yes my alternator is charging cause I always check it on my gauge cluster..

LIST OF WHAT'S ALREADY BEEN DONE:
-battery control module
-front auxiliary relay by the auxiliary battery
-new battery/both aux and rear
-alternator
-voltage regulator
-Mercedes Star Diagnostics Scan..no luck..

If any of u have any other ideas of have had this issue and know the answer.. let me know and fill me in asap! Please comment or text me or pm me.. fastest way to reach me is through text so please fill me in..located in soCal

909-906-8052

 

I plug it in when its cold and its been good since.

 

Plug wat in wen it's cold?

 

Audio gateway

 

I don't quite get what u mean? U mean the actual gateway or just the fuse?

 

OR from the SAM module?

 

They are common to cause a draw. Confirm by removing the fuse. If that's what it is then it needs replaced.

 

Does your alarm siren beep, or are you able to get your siren to sound

I had a battery drain issue recently where my main battery would have 0% left in the morning

I found the batteries in the siren had leaked and had shorted the board which was turning the alarm on when I locked the doors but not sounding

The batteries are non replaceable and will eventually leak on all models at life end if not replaced with a new siren

 

when I click my alarm it beeps 3x's when I push lock. Where is this part located exactly that you say leaks?

 

If you do a proper current draw test to find out how many amps or milliamps of current it's drawing at rest it would be much easier to determine whats causing the draw. There are far to many electronics on the car to just be making guesses as to what the problem is. So find out the exact draw and it would help

 

I had a similar Battery drain issue. I would get low battery warnings and then one morning the car would not start. The Battery in place at the time was a 3 yr old MB Primary and Secondary battery.
If your battery runs down do not jump start these cars, with the electronics being finicky a surge can easily cause issues. Instead plugin a battery charger.
I tracked down my battery drain issue to the OBDII bluetooth module being plugged in. I since have removed it and have not seen the issue in over a month now

 

Try taking the fuse out for the passenger side seat module it's in the interior fuse box I had the same problem it does not show a fault with sds

 

they all drain. nothing you can do about it. if not going to drive it for abit just plug in a trickle charger and you will be fine.

 

Obtain a quality multimeter that will measure down to microvolts and use the easy way in the attachment. Warning: math is involved. Keep alive circuitry only requires milliamps; sounds like you have something drawing multiple amps.

 

If OP can't even provide the amount of draw wether in A or mA I pretty sure this procedure will be way over his head.

 

if an Audio Gateway normal draws 5-10mA at rest and a defective one is drawing 2A at rest then there is something you can do about it.

 

LOL! Math is hard!

 

definitely much harder than measuring amperage

 

Math is no problem for me.. I'm Dian so it comes naturally. . Hahahaha

 

what was the issue ? I'm having the same problems right now....

 

Resurrecting this thread as have a similar problem with my w211.

You need a high current amp meter or some way of measuring the current drawn while your car is locked. Lock the trunk lock with the trunk open, otherwise the car won't close.
with the battery connected Connect the amp meter between the negative lead of the battery and the car's wirring.
this is very important that the battery should be connected to the car before disconnecting the cable.
Otherwise the high inrush current for the car starting up, SBC self test and so on will fry the amp meter unless it is a beefy 50A+ one.

Keep this amp meter in series and monitor the current flow. It should go below 0.1Amps pretty soon after the car sleeps. And Under 0.05 after 10mins or so.
If it is over 1A, you battey is probably also 100Ah, when new, goes down 10% each year if you are lucky, so you do the math....

After getting familiar with current measurement, disconnect the red wires from the panel near the spare.
My bet would be on the second one counting from the bottom.
Procedure: remove the battery negative lead and the amp meter so bat would be fully disconnected.
Remove the wiring for the red cable, second counting from bottom. (it is for the instrument cluster fuse box)
Attached the battery, close the car from the key, wait a minute and then connect the amp meter per the procedure described before.
LEave it a few minutes, the current should drop to almost 0.
LEt's call this method "restartAndShutdown()"

If not, try a different red wire.

Then go to the corresponding panel, remove the fuse one by one and restartAndShutdown() again and again until you see which is the modul which consumes too much.
You fave to restart each time probably for best results.

Thing is that the module itself won't consume much, but by sending unwanted data on the CAN bus it keeps the car from shutting down.
You won't notice a current drop as soon as you plug the fuse out. But you will notice one in a few seconds after. The current will drop gradually as all the modules are shutting down.

Basically it is like the windows shutdown procedure when it is asking you: you have unsaved documents, are you sure you want to shutdown?

I still don't have a solution to stop the drainage unless i remove the module's fuse.
Probably a module replacement would do, i am still investigating, will revert with a solution if i will find one.
This applys to all w211 probably.

 

Hi, please How to:Clean Full ASSYST Memory for W211
Thanks

 

went through the same. replaced the same parts as you.

in the end ALARM module behind front wheel well. Time to replace it.

 

Did you ever find the answer?

 

Mine was alarm siren, and then the stereo amplifier not turning off.