What runs off this cable??? Please help!
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Newbie
Joined: Apr 2011
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s500l w220
What runs off this cable??? Please help!
Hey guys,
Im hoping someone can help. I have had a very bad battery drain on my w220 and after a long time diagnosing i have traced it to a red wire on the right hand side boot/trunk wall, after disconecting this cable, the drain drops. I just have know clue as to what runs off it, do all the SAMS? the altenator? i hope someone can help because im so close but so far now
Thanks in advance
Im hoping someone can help. I have had a very bad battery drain on my w220 and after a long time diagnosing i have traced it to a red wire on the right hand side boot/trunk wall, after disconecting this cable, the drain drops. I just have know clue as to what runs off it, do all the SAMS? the altenator? i hope someone can help because im so close but so far now
Thanks in advance
MBWorld Fanatic!
Joined: Dec 2004
Posts: 3,063
Likes: 26
From: Tampa, FL
2005 S500 4-Matic, 1978 450SL
Welcome to the forum.
The block shown does supply power to the SAMs. Because cutting power to the SAMs stops your battery drain, it is likely that some device is preventing shutdown of your CAN bus, which runs through the SAMs. When the CAN bus remains active long after it should shut down, you will have excessive battery drain (sometimes called quiescent drain). You will need to find the malfunctioning component.
You don't provide the model year of your car, which makes further comment difficult. One cause written up on the forums for older W220s having a nav CD slot built into the COMAND unit is the nav CD continuing to run after shutdown. If you have such a unit, try ejecting the CD (yes, it's a pain, and no, I don't have a fix) and see if it cures the problem.
Other than that, the posts under "Electrical System" and "Battery Drain" at http://www.benzworld.org/forums/w220...tart-here.html may help. Several other possible sources of the problem and steps to identify them are discussed.
It is also possible that you have a bad SAM (W220s have three of them) - but I would not start there unless there are signs of water damage to them (usually from a plugged drain in the plenum in front of the windshield). See the Encyclopedia link under "Body" and "Water in Car" for more. SAMs are expensive, and other potential sources of the problem are less expensive, which is why you want to consider SAMs as a last resort.
The block shown does supply power to the SAMs. Because cutting power to the SAMs stops your battery drain, it is likely that some device is preventing shutdown of your CAN bus, which runs through the SAMs. When the CAN bus remains active long after it should shut down, you will have excessive battery drain (sometimes called quiescent drain). You will need to find the malfunctioning component.
You don't provide the model year of your car, which makes further comment difficult. One cause written up on the forums for older W220s having a nav CD slot built into the COMAND unit is the nav CD continuing to run after shutdown. If you have such a unit, try ejecting the CD (yes, it's a pain, and no, I don't have a fix) and see if it cures the problem.
Other than that, the posts under "Electrical System" and "Battery Drain" at http://www.benzworld.org/forums/w220...tart-here.html may help. Several other possible sources of the problem and steps to identify them are discussed.
It is also possible that you have a bad SAM (W220s have three of them) - but I would not start there unless there are signs of water damage to them (usually from a plugged drain in the plenum in front of the windshield). See the Encyclopedia link under "Body" and "Water in Car" for more. SAMs are expensive, and other potential sources of the problem are less expensive, which is why you want to consider SAMs as a last resort.
Last edited by Skylaw; Apr 12, 2011 at 10:36 AM.
Thread Starter
Newbie
Joined: Apr 2011
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s500l w220
Thanks Skylaw, im going to retry the fuse pulling over the weekend but leave a longer period of time between pulling the fuse and testing drain to ensure the car goes to sleep. I removed the rear sam as the cable i refered to connects directly into the fusebox/sam modlue but on visual inspection there is not sign of damage. I will update as i progress and many thanks for your help!
Member
Joined: Dec 2003
Posts: 109
Likes: 1
From: NJ
S500 1997 + S600 2005
Skylaw:
Then, is it safe to say that unless needed at a particular moment for some reason, it is advisable to keep all CDs ROM out of COMAND, and the NAV CD ROM as well?
Due to my wierd conclusions, I used to keep them out until resently because while the NAV CD ROM is in, the system activates the drive, thus putting more mileagle in it, if you will, for no purpose at all.
Will take them out again unless going on a trip.
Then, is it safe to say that unless needed at a particular moment for some reason, it is advisable to keep all CDs ROM out of COMAND, and the NAV CD ROM as well?
Due to my wierd conclusions, I used to keep them out until resently because while the NAV CD ROM is in, the system activates the drive, thus putting more mileagle in it, if you will, for no purpose at all.
Will take them out again unless going on a trip.
