Any way to get rid of Aux Bat Malfct warning without replacing the voltage converter?
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From: Palm Beach Gardens, FL
Porcelain Bus
Any way to get rid of Aux Bat Malfct warning without replacing the voltage converter?
2016 C450 1 month out of warranty with Auxilliary Battery Malfunction Warning that is very annoying. Tried disconnecting plug from negative battery terminal without success in eliminating warning. Before doing that the auto start stop was still working even with the warning present. Car battery was replaced 6 months ago and car is running fine. How can I get rid of the warning without investing in a new voltage converter? Thx in advance
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From: San Jose area
'19 E63S sedan
2016 C450 1 month out of warranty with Auxilliary Battery Malfunction Warning that is very annoying. Tried disconnecting plug from negative battery terminal without success in eliminating warning. Before doing that the auto start stop was still working even with the warning present. Car battery was replaced 6 months ago and car is running fine. How can I get rid of the warning without investing in a new voltage converter? Thx in advance
Thread Starter
MBWorld Fanatic!
Joined: Dec 2002
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From: Palm Beach Gardens, FL
Porcelain Bus
From what I have read from the forums, the voltage controller mainly retains power for the auto start stop system. What other known functions does it have?
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From: San Jose area
'19 E63S sedan
The division of labor between the main battery and aux "battery" is complicated, but under normal operations the aux battery runs everything but the starter. The logic behind auto start is owned by the aux battery, but the actual turning over of the engine is the main, starter, battery. That said, when the aux battery fails, a relay hands the responsibilities to the main battery for a while, but as the system degrades non-essential consumers are disconnected in priority order. First to go are windshield defrosters and seat warmers. Then things like infotainment. When safety is threatened, the car goes into a sort of limp mode.
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A gaggle of MB's
1. With your VIN# call your MB dealer's Part's Dept and get part# and quote for the genuine MB replacement
2. With that Part# - go to Amazon and do a product search - frankly there are China non-OE and non-MB rebuilt's as low as $56 - and on other internet websites new MB as low as $110. Note - there are a LOT of China knock-off, and a LOT of 3rd party supposed "re-builts" in the market, and if you order a "genuine" new MB part make sure you order from a reputable web site
3. There are YouTude videos for the replacement procedure under the passenger front carpet - takes 15min really
Go forward, never go back... keep the beat !
2. With that Part# - go to Amazon and do a product search - frankly there are China non-OE and non-MB rebuilt's as low as $56 - and on other internet websites new MB as low as $110. Note - there are a LOT of China knock-off, and a LOT of 3rd party supposed "re-builts" in the market, and if you order a "genuine" new MB part make sure you order from a reputable web site
3. There are YouTude videos for the replacement procedure under the passenger front carpet - takes 15min really
Go forward, never go back... keep the beat !
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W205 2015
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W205 2015
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A gaggle of MB's
There are YouTube video's for the W205... easy to work that part thru:
3min Step-By-Step video:
Real time 17min replacement video:
$11 Amazon MultiMeter:
3min Step-By-Step video:
Real time 17min replacement video:
$11 Amazon MultiMeter:
Senior Member
Joined: May 2019
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C400
none really, you can disconnect it from the battery ground its a 2 pin harness, and that will defeat the stop-start thing and everything else stays the same.
Super Member
Joined: Dec 2016
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2018 C43
Also have this disconnected for past year and so far so good. The way I see it, my main battery will be charged without interruption, and starter will be worked way less for $1 a week more on gas.
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C400
