2005 E500 wagon battery drain
 

... Just about to break down and have the dealer look at this one.

Both batteries brand new along with alternator. Battery will still drain overnight. Sometimes it will start and show battery low message in red. Once you drive the car for a while it will be the battery message in black. After fully charged it goes away. Park the car overnight and it will repeat.

We have pulled every fuse in the car for testing and there is still a drain on the battery. :mad: Both batteries test fine and the alternator tests fine.

Any ideas?

That could get expensive and you'll have to pay even if they don't find the problem. It sounds like you have eliminated the easiest checks.

If you are concerned about the car not starting in the AM, you could pick up a small charger designed to just cover the loss from the drain. Sometimes called a battery tender or maintainer. They are pretty inexpensive. I think I paid $8 at Harbor Freight.

do this...

connect a multimeter (better yet a test light) in SERIES at the battery i.e. connect the tester between the battery and the cable.

at this point you will find that there is a voltage draw (enough to kill the battery overnight).

start pulling the fuses ONE by ONE. When you pull the fuse with the fault, the voltage draw drops dramatically (it won't drop to zero because you still the clock running).

This test will determine where your problem lies. At least it will tell you where to look.

I think this forum just saved you a few hundred smackers in diagnosis fees!

I wish...

That's exactly what we did. Every fuse 1 by 1... Still has the drain.

Can't tell a customer I just sold the car to that he's SOL... Either I figure out a way to fix it or buy the damn thing back.

Off to the dealer it goes, I guess. I've been about battery control modules, Command navigation and SBC causing problems like this. Way out of my league. Need SDS. Been thinking about buying one. Since this seems to be the way of the future, I guess I should.

I'm curious to find out what the dealer found.

I have a freind in Turkey who was eating off my ear for owning a MB, he had a problem with his car - it was some diesel E that had the ghost drain issue.

His problem was rectified by a big relay type item and it cost him quite a wallet gouge.

Did you try to test the alternator diode brigde?

+1 here

Tyler, most common draw on the W211's are... Rear Sam, tele-aid, Dome lamp, & command.

bump

Answer:

Cup holders...

Previous owner spilled soda on the height selection for the airmatic. Made the control module go cooky. $900 poorer.