HELP! W220 400cdi keyless go battery drain

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S400 CDI

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Feb 17, 2016
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S400 CDI (W220) 2003
Hi eveyone,

I have recently purchased a s-class W200 400 CDI from 2003.
When I just had the car everything was working fine, however since a few weeks the Keyless-Go is not functioning anymore. It kept saying card not recognised.
This was not a real problem to me(although it was a nice option).

The real problem just started a few days ago when my battery was flat in the morning. First thing I did then was having a new battery installed but the next morning that was empty as well.

Since the only thing that was not functioning on the car was the Keyless Go, I removed fuse 58(Keyless Go). This kind of solved the problem, the battery is not draining empty any more. Unfortunatelly additional issues are now that the remote central locking is not working and my comand has no radio reception anymore, this of course is very annoying.

Does anybody has any suggestions how this can be fixed easily? If i put back fuse 58 the radio signal and the central locking are working again but my battery will be flat in just a few hours.

Many thanks for your help.
 
You need to find out why the Keyless Go has stopped working and then investigate the battery drain.

Recommend visiting a Merc indie and getting the car on STAR for starters.
 
Thanks whitenemesis for your reply.

After the Keyless Go stopped working I went to the garagage, they checked the car with star diagnose and there where no errors on the Keyless Go. They also tried to search for the Keyless Go card with the star software which was unnable to find the card. They suggested to order a new card but I did not have a good feeling doing that so I refused. Of course I also tried to install new batteries in the card but that did not help either. I must admit this was two weeks before the battery first drained empty, but I am affraid if I go back to that garage now, they will just charge me for the diagnosis without finding any errors.
 
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Why did you "not have a good feeling" for the suggestion of a new card?

Suggest you try a different garage. Whereabouts are you?
 
Because the lights on the card are still burning when I press the button and that nothing harmful had happened to the card. I know this doesn't have to mean anything and that the card can still be broke, but I think the fact that the battery is now draining on fuse 58(Keyless Go) proves that at least something inside the car must be wrong too.

I live in the Netherlands.
 
If you have no radio reception and no remote unlocking you have lost power to the antenna amplifier that receives those signals. Which on S class is a single pack at the top of the rear window.

Does it return if you plug fuse 58 back in ? According to wiring diagram it shouldnt be fuse 58 it should be fuse 60 (so are you sure you removed F58, or did you knock out F60 at same time)

58 should be second fuse in from the right on the top edge of fusebox 7.5Amp

R
 
Hi Richard,

Thanks for your reply.
Please find attached a picture of the fuse that I removed.

According to the diagram and your post this should be fuse 58, and yes as soon as I reinsert this fuse everything is working again.

I had my car star diagnosed yesterday again and there are no errrors on the Keyless Go (or anything else). The diagnosis was done with fuse 58 installed.
 

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That is fuse 60. 58 is the orange one. You need to count the gaps which would have fuse holders in then if you had extra options

Richard
 
Thanks Richard,

I guess you are right about that fuse.
The problem has been solved anyway, I disconnected the cars battery for half an hour and then reconnected it again.
The battery drain is gone and my car started again last morning.
I have no idea what has caused this, but I am glad it's over.
The Keyless Go is still not working, it keeps saying card not recognized so I guess the card is broke after all.

Can anybody tell me if it is possible to order a smart key instead of a card for a W220 from 2003 ?
 
where did you buy your 220 from? id love a 400cdi but never seen one for sale anywhere?
 

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