Is it the Altenator? COMAND screen and other options shutdown
Thread Starter
Newbie
Joined: Mar 2014
Posts: 8
Likes: 1
From: Clinton, MD
S550 4matic
Is it the Altenator? COMAND screen and other options shutdown
I was driving the other day and all of a sudden all of my options malfunctioned. The warning messages for the ABS, EPS, Parking assist, blind spot assist etc. all came on one after the other, then the COMAND screen shows a message saying " please restart the engine or COMAND will shut down in 3 seconds." Mind you I was driving at the time, so eventually it went black and the red battery symbol popped up. I assumed it may have been the batteries, so I had them both replaced. As I am driving along again, the same thing happens. The car basically feels as if you are driving through quicksand. I luckily was close to home and made it into my garage. After ding some research, I was wondering if anyone else had the same issue and was it the Altenator or something else? I heard people mention the SAM control module in some of the other blogs. Any insight is appreciated. Thanks.
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Joined: Jul 2007
Posts: 1,904
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S350 BT 4MATIC
I had one system come up and do that and I went to the dealer and they found nothing. Hopefully next time it happens I will be near a Tech Workstation.
If you do not have anyone near you with a XENTRY/DAS laptop, then the dealer is the only option to get the alarm codes and potential solution.
If you do not have anyone near you with a XENTRY/DAS laptop, then the dealer is the only option to get the alarm codes and potential solution.
Junior Member
Joined: Aug 2014
Posts: 57
Likes: 10
From: Zurich
S500 4M L
I was driving the other day and all of a sudden all of my options malfunctioned. The warning messages for the ABS, EPS, Parking assist, blind spot assist etc. all came on one after the other, then the COMAND screen shows a message saying " please restart the engine or COMAND will shut down in 3 seconds." Mind you I was driving at the time, so eventually it went black and the red battery symbol popped up. I assumed it may have been the batteries, so I had them both replaced. As I am driving along again, the same thing happens. The car basically feels as if you are driving through quicksand. I luckily was close to home and made it into my garage. After ding some research, I was wondering if anyone else had the same issue and was it the Altenator or something else? I heard people mention the SAM control module in some of the other blogs. Any insight is appreciated. Thanks.
Junior Member
Joined: Aug 2014
Posts: 57
Likes: 10
From: Zurich
S500 4M L
My alternator fault was strange - it shows on display (enter to service menu Hold button and left OK) that charging on 12,5-14,2 (never 14,4) and sometimes immediately drops till 11.0 > 10.0 below this value Merc was shut down on the middle of street in seconds 
I thinking alternator had short inside. Replaced to new one and charging ALWAYS is 14,4V
I thinking alternator had short inside. Replaced to new one and charging ALWAYS is 14,4V
Last edited by maniekS500; May 12, 2015 at 12:25 PM.
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Thread Starter
Newbie
Joined: Mar 2014
Posts: 8
Likes: 1
From: Clinton, MD
S550 4matic
So it was the Altenator. My father and I replaced the alternator and now the car runs great. I purchased an aftermarket one from NAPA auto parts for $400, considerably less than the $1400 Mercedes charges for theirs. Accessing the Altenator is somewhat of a nightmare, but we struggled through it. We ended up having to remove the radiator fan and the air filter connection in order to be able to actually remove the unit. I can understand why the dealerships charge so much to do the job. It took us almost 8 hours to complete, but some of the time was just figuring out how to approach aspects of the job.
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Junior Member
Joined: Aug 2014
Posts: 57
Likes: 10
From: Zurich
S500 4M L
Great that you have it sorted !When my alternator died I took car to workshop (starters and alternators specialist). They sold me renewed alternator and replaced it for 250$ in total (alternator + replacement and collected old alternator). Job took 2hrs - mechanic disconnected rear battery, removed radiator and replaced alternator). They offered 1 year warranty on the device with no mileage limit.
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Junior Member
Joined: Aug 2014
Posts: 57
Likes: 10
From: Zurich
S500 4M L
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