DFW01E55

I came back from a 1 week trip on June 25 to find a dead battery. Okay, no big deal, it's the original battery.

MB came out and replaced it.

Came back last night from another week away and the new battery is dead.

I did a search and one guy mentioned the instrument module as the possible culprit and the alternator also recieved honorable mention.

Any other CL experience out there?

04-E55GMAN

I had a very simular problem, and it turned out to be water leaking into my trunk and killing the battery.

Check for moisture in the trunk.

sprins

My W220 S-Class has just been sent to (probably) have the alternator replaced. Enough current to run, but not to charge the battery.

whoover

Rear SAMs are very popular culprits on 220s. Would guess they act up here too.

C43AMG

Voltage regulator on the altenator.

DFW01E55

Thanks for the replies.

No water in the trunk.
Alternator checked out okay by MB tech when he replaced the battery.

Rear SAMs? Surface to air missiles? Cool option but I didn't get it.

C43AMG

I may be wrong but I thought a bad voltage regulator won't show-up on a bench test of a alternator, it has to be specifically tested.

whoover

No firepower involved. Where cars used to have a "fuse box," they now have multiple Signal Acquisition and Actuation Modules. These monitor signals on the networks and do things like turning lights on and off (figuring out if a bulb has blown in the process). When a SAM malfunctions, the symptom is often spurious battery drain.

DFW01E55

Thanks guys, I will point out these ideas when I take the car in for service.
Solving electrical problems is not one of the high satisfaction experiences with most dealers.

whoover

CANs and SAMs make it very complicated. The common cause for the battery drain is the CAN B network not "going to sleep" when the car is off. A bad SAM can do this. A good link, both to help you appreciate the complexity and to show you the diagnostics the dealer should be running, is

http://www.babcox.com/editorial/ic/ic030538.htm

tkracing

Mine just did the same thing after not driving it for a week.

Al E

My CLS55 is at the dealership now. They are trying to determine why the battery goes dead and the car will not start.

bltserv

Left mine alone for 4 days at airport.
Did the same thing. Dead Battery.
Mercedes came out and replaced next day. It had a dead cell.

Mine seems to be something with the window control module.
Been suggested here before.
When my windows fail to go up after closing the door.
It fails to do it every once in a while.
Seems like way less often now that the battery was replaced.

I was at the dealer getting new tires for my SL55.
There was a guy there with a new S55.
It had a dead battery after being 4 months old.
This guy was having a real hissy fit over it with my SA
My SA told the guy "A Battery is like a light bulb" Sometimes they just fail.

DFW01E55

Mine is sitting at the airport waiting for me.

While driiving into the airport 48 hours ago, the radio suddenly went quiet and dark. No response to the off/on - nothing, just dark.
Less than 5 minutes later, it suddenly comes to life.

It will be interesting to see if there are any after effects when I get back.

Edit: Started up just fine but someone hit the right front of the bumper with some soft black rubber and made a heck of a mess. I love leaving my car at the airport.

Lov2xlr8

i had the same problem.
i ended up being that leave get in the grill and blocked a sensor. so when the car turned off the sensor told the car that the engine was very hot and the fans turned on. ask your dealer to check all the sensors in the front of the car.

sprins

This happened to me too in my SL55, which has no electrical problems BTW. I just yought WTF and before I could get angry the radio went back on... Never happened before and hasn't happened after... Twilight zone?

On another note, the workplace is still working on my W220 which was towed away with an dead battery some time ago and the suspicion is now on the door lock module, which seems to go beserk and drain all the power when the car is off. Tomorrow will be day 16 (!) that the car is in the workplace and I'm planning a little visit as I am getting a but tired of this sh¡t with these electronics. Or rather without...

sprins

My tech today too mentioned the rear SAM control module. Either short circuit or water damaga. The latter seems unprobable as the car hasn't seen rain in two months...

bltserv

My 2005 SL55 has the same "twilight zone" radio. Has happened like 3 times now. Start the car. No radio/cd volume. Its on, you can see the CD
changing tracks. But no volume. One time it gave a slight tone.
Turn the car off. Restsart. Everything is fine. Has not done it while its running.
Just on startup. Rod Serlings ghost is in my car.