Yestodag i got a msg on my cars computer telling me left brake light rear was out, i changed it... i parked the car and came back to it 10 hours later and the battery was almost completly dead! I dont understand this, i have searched about this problem all over the net, and som said it could be the seat module, but i dont think i got this? Is this for moving the seat back and forwards? Some said it could be comand not switching off... i tried to observe this, and true.... when i take the key out, the ON light on comand stays on, and the comand fan does not stop it just goes and goes... i tested it for 30 min, and still the light ON was on and fan was running....

Now, all this happen after bulb change, could that have to do with anything? I tried to take the fuse out for the comand, and drove for 1 hour... and now the battery works perfect....... so why is this? Why is comand doing this? What can i do to stop it?

Some told me to disconnect command from the CANBUS, but how do i do that? I dont even know what a canbus is? - and if i found the canbus how to i disconnect command from it?

Thank you all!

 

Hi

You don't state model, age etc.

I don't think your problem is linked to the blown buld unless the bulb wasn't actually blown!. Did you check the old bulb for a broken filament? Have you tried putting the old bulb back?
I believe it may be just a coincidence and that there is something more fundamental wrong.

How long have you had the car? Have you ever had problems on this car before with flat battery? Have you had any other problems. etc

You state Comand is staying alive for some reason. I don't know much about Comand but you refer to an ON light. Can't think why there is such a light unless there is also an On/Off switch. I don't suppose you are referring to the red (should be flashing) security light are you?
You also refer to a fan staying on. How do you know the fan is stayimg on? If you open the doors to listen this will wake the computer up which may be the reason you think the fan is on all the time.

If such devices remain on you will get a flat battery even if your battery and alternator are in good order.

Everything should shut down (except certain prescribed systems) after about 30 mins in order to protect ability to start after a period of inactivity. Check by leaving the interior light on manual. It should go off. Does it?

So why is system not shutting down? System is controlled by the Body ECU in the big black box under the hood (subject to model etc.)


The best way to check what is going on is with a multimeter in series with the battery which can be observed from outside the locked vehicle.

You hasve currently provided insufficient info to determine what is wrong.

However, as a wild card.....Is your security system working correctly?

Security (ATA), the interior lights, door locks/switches and the "Bulb" monitoring system are all linked by means of a CAN connection between the Body controller and the security system. A faulty PSE (Pneumatic/Security control unit) has been known to cause this sort of problem since the security system is one of the systems that remains alive when most of the ECU's/computers are asleep.

Need to start finding out exactly what is staying on which will lead you to the why. How handy are you with a multimeter?

Finally in answer to your request... What is CAN. (Controller Area Network)
Modern vehicles can have around 30+ different "computers" controlling different functions around the car. A/C, ABS, ASR, ESP,SRS, EMS, Trans, Cruise, ICE etc. etc. These controllers (ECU's) need to be able to share data. This is achieved by the CAN whuch is simply two twisted wires (MercedesBenz is usually white/green) or coaxial cable which connects the ECU's together and permits transmission of digital signals betwee them. Disconnecting the CAN may help in determining what is wrong but this is not as easy as it may sound since CAN connections are integrated into multiconnectors. Disconnecting the CAN is also likely to prompt all sorts of Fault Codes / Warning lights which may need to be reset by the dealer.

Hope this helps in some way. let me know how you get on.

Stuart.

 

Hi BXTC,

I've just remembered. Are you the guy with the oil in the ME ECU?
I didn't get a picture of the contaminated part or an explanation as to where the oil came from.

Are we talking about the same car?

Could there be a link since the Body controller is in the same underhood compartment as the ME controller.?

Stuart

 

Hello!

Yes i am the same guy with the ME ECU. And yes its the same car. I did send you a email with pictures and a explaination why and how the oil came into the ECU, or i mean how they think it get there.

My car is a C230k sportscoupe from 2001. Perhaps it can be some kind of problems again from the ECU, is it safe for me to disconnect the plugs on the ECU to see if there is any kind of oil there? Another infomation i think i should have said was, when i got the change bulb on the display, it was raining very much, actually they said in the news that it rain as much as a whole summer on 1 day, and i was driving it that rain... i dont know if the rain broke the seal or penetrated into the ECU compartment?

After you told me about the bulb, and if it really was blowned i just checked it, the blub is rather "black" on the top, but to be honest it doesnt look blown, it actually looks intact, i will test the bulb later today. What i meant was with comand is, there is a ON/OFF switch on the comand, all though its just shows ON, i found a picture of a comand ITS NOT MY comand but its the same model : http://www.intest.cz/images/comand_1.jpg -- look at top left, the ON switch, that stays illuminated even after i shut down the car, i know the fan is on cus i stay in the car to see it shut off.... but i have noticed that after about 5-10 min the fan actually shuts off, but the ON is still illuminated and it shouldt.

How do i check if the security system is working ? To answer your quistion about the multimeter hehe, i just bought one, so i am not so handy with it, neverthoughless i will try if you explain how i should do it - thanks!

So to add things up:

1) Can i unplug the ECU to see if there is oil in there again?
2) I will check the bulb to see if it actually is blown

I will come back later with and update.

One last thing, if there is some kind of oil in the ECU, how can i clean it, without damageing the ECU it self.

 

Okay here is an update.

Last night i parked the car, and pulled the fuses for comand and for the seat module. This DID NOT HELP. The battery was still flat when i got to the car today, and this time it wont even start.

I checked the bulb and yes, it is blown, i even checked it in another car and with a battery. I am thinking could it be that the battery is just dead and i should get a new one? Even though i dont think this would help anything?

Still waiting on answer on if its safe to unplug the ECU to check it

Thanks

 

Hi Andrew,

Unplugging the ECU isn't a problem so long as the ignition is OFF.

Heavy rain = Water ingress = Lots of electronic problems. Which ECU has got wet I wonder.??

OK the bulb was blown. I don't discount this theory however. Where is your PSE situated. Could water (a single drop in the wrong place is enough to wreck it) have got to it?

Battery could just simply have died due to age but you state that the Command warning light is behaving differently and suspect power is not shutting off. What happened when you manually set the interior light. it should go off after a given time. Did it?

You need to use your multimeter to determine what current is being dawn from the battery. Put the ammeter = multimeter in SERIES (not parallel) in order to measure current. DO NOT ATTEMP TO START THE CAR in this configuration. If you do it will blow your multimeter!! Plot current against time from turning the ignition off. Current should drop to milliamps after a given time. Suggest you plot over say 30 mins and see what happens.

Going away for a couple of days, Stuart

 

Hello mate, thanks for your time.

When i manually set the interior light, it does go off within some time yes. I have concluded that it is not the comand system as i had pulled the fuse before i parked the car and still have the same problem.

You state "Put the ammeter = multimeter in SERIES" What do you mean by this, in series? And where should i "put" it ? Exactly which ECU do you think has gotten wet, and what is a PSE? Perhaps becuase i live in Sweden we have diffrent names for the stuff hehe..

What should the current be at, at a car that works normally?

Thanks.

 

This is the multimeter i got -
Can this be used?

[IMG]local://upfiles/13491/6BEE231F932E4FCBA8DC214FB7FABFA1.jpg[/IMG]

 

I just got a new message on another forum saying that the W203 does not have a PSE PUMP, is this correct? Sleepwalker help would be great here mate!

 

Yes. Your multimeter is fine.

However Iif you don't understand SERIES (Current) versus PARALLEL (Voltage) I think you need some help from somebody who understands electrics.

You need to measure current drain from the battery against time from the point at which the ignition is turned off and the vehicle secured.

I don't have the exact current drain for your model but would expect it to be about 50 to 100 milliamps once the ECU's have gone to sleep. If it is 500 milliamps (half an amp) or something close to this it is no wonder the battery goes flat.

Stuart.