trombone

Here it is: key goes in the ignition, turned to position 2, everything lights up normal.

I start the engine, it fires up OK, next second center console goes black, steering wheel returns to exit position, no power to windows, roof, windshield wiper, turn signals, seats.

Instrument cluster stays normal and scary malfunction messages displayed one after each other: airmatic, FPS, BAS want me to see the workshop.

Driver in mild panic mode.

Malfunctions removed by reset, engine turned off, key removed, I let the cluster light go off as they should.

Next I start the engine again, everything stays powered fine as if I dreamed the whole episode.

Then, after one day, or one week, or just at the next start up, the partial power outage and the eventual successful start replicates.

If do not care to get the lost power back, head lights, tail lights still stay operational, car drives OK, power steering, brakes work OK. Ride a bit rougher, but no loss of air or height.

Battery gives 12.37 V, is it not low a bit??

Shall I get a new battery, or should I look for a bad connection which re- and disconnects? Where?

The power outage never occurred while I drove the car. Always after a parking period.

You help will be really appreciated.

George

S600Keith

Holy smokes...that's a weird one.

sakodik

I had similar symptoms and it turned out to be a bad alternator. Yours does not sound like it, but something to look at.

SFBIGBODY415

Sounds like an alternator issue. Seems like the car is not getting the proper charge while parked or driven making your computers act crazy

driveability

Well since it resets the steering wheel for exit, maybe an ignition switch issue. I know on many cars the head lights aren't routed through the ignition key so they should work fine. Just thinking out loud here. Surely a connection, a main one set before the hundreds of tributaries which branch off and are fused by component. the idea the warning lights seem to be reset support the above. Your battery voltage is OK, sure is a strange one. These are the ones I love to work on, assuming I can find the problem within a few hours. After that it becomes a living hell. good luck

tusabes

I can virtually guarantee you its a weak battery and/or weak alternator.

These cars have a VERY high demand on the battery and it might even "test good" but not be strong enough to properly power everything.

Id try a new battery first and see if that fixes it. If not , do the alternator. Autozone sells the battery cheap, like $109

driveability

sure a battery or alternator are main power feeds. A car when it starts up by using a starter takes a lot of amperage so the fact its cranking tells me the battery is likely OK. With simple tools a volt meter one could read the voltage at the battery during the short period of time the starter runs just before the engine starts. A reading below 9.6 volts would be a problem. Meaning the battery is bad or just low. Sure it could be other things but lets just say that. This a 5 minute test. The idea the battery shows over 12 volts tells me that all the cells are OK. 2.1 volts per cell so a bad cell would read somewhere around 10.5 v. given the advice about the battery & alternator I would lean more toward an alternator if I had to guess. I don't like guessing but who does. Having so many computers each of with have a minimum voltage circuit shut down an alternator is a good guess. I own a CL65 which has a water cooled alternator ( those German engineers are great !) like a diesel transit bus a friend of mine maintains WOW. All guesses, I'm glad its not a 747 .

AH1W-COBRA

does the "glitch" occur in the morning on the first start or completely random?. i had a EIS that would do the exact same thing but only below 34 degrees. i made a video of it and took it to the dealer. they finally had to leave the car outside at night and bring the diagnostics to it and sure enough the EIS gave a fault code. im not sure why the code wasnt stored but the dealer was so glad to fix it that it didnt matter. i still have the warranty bill and the list of parts that they threw at it was crazy.

trombone

Thanks to all of you for bringing up great ideas.

Yes, the problem occurs mostly in the morning at the first start. Once it annoyed me at the grocery after shopping.

But, no glitch today, all worked normal!

Temperature is hardly a factor, my car is garage kept and the weather is not too harsh anyway.

Yesterday I visited the dealership for advice (it is free), at the service reception the guy hinted that a SAM (signal acquisition module, or what) is most likely the culprit, price for diagnose + new unit in the high hundreds, so I would not rush back very soon.

I give it a couple of more days and collect data. I also blamed the battery, there is no date on it and I have no idea how old it is. The service dismissed the idea, but I am skeptical whatever they say.

Is it OK to use a battery charger without disconnecting the unit?

The ignition switch did not occur to me, thanks for the tip, I'll keep an eye on it.

I'll keep you posted on any significant change or possibly, a solution.

George

tusabes

Don't charge it while attached to the car
If you don't see a date code on it just swap it out

A w220 battery can easily have enough juice to start the car , but not correctly power the electonics . That it happens when first started , while the battery has drained a bit all night and from cranking , before the alternator has charged it up a bit , points to battery to me.

I'll repeat - w220 is very sensitive to weak batteries , even batteries that test just fine on battery testers and start the car just fine may still be too weak

AH1W-COBRA

all the symptoms other than the console going black are controlled by the EIS. one of it's many functions is to recognize which key is currently in use and set all accessory functions to that drivers settings. they replaced two sams in our car prior to finding the EIS as the problem. good luck and as other experienced members are saying, replace the battery!. i replace ours every two years.i get it at napa, has german tags/language and is the exact same battery that is installed at the factory. approx $300.

RedC320S

The battery can read a decent voltage but may not have the amperage to satisfy the car's needs. A load test of the battery would tell you this.

trombone

New OEM battery has been installed. So far all so good.

trombone

Since the new battery was installed I drove the car 8 days, normal every day errands with several park and restart and not a single occurrence of the annoying power loss.

So, let's accept that the battery was too weak, even though it did not seem to be.

Thank you friends, the Forum did it again.
George