Aux battery malfunction
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Newbie
Joined: Apr 2021
Posts: 3
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2014 E350 sport
Aux battery malfunction
2014 w212
Auxiliary battery malfunction came up on dash I checked battery and had corrosion on positive side I checked volt battery has 10.3 volts I cleaned everything put back together and started car still 10.3 bolts I took positive off while still running and tested the cable alone no volts any ideas why ???
Auxiliary battery malfunction came up on dash I checked battery and had corrosion on positive side I checked volt battery has 10.3 volts I cleaned everything put back together and started car still 10.3 bolts I took positive off while still running and tested the cable alone no volts any ideas why ???
Joined: Nov 2016
Posts: 7,847
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From: Maryland
2015 SL400 (M276 Turbo), 2014 C350 Sport (M276 NA), 2004 SL500 (M113), 2004 Audi TT225 (BEA)
If you are trying to test your alternator, get a proper tool. I have no idea if you need to have the battery connected for the alternator to provide voltage to charge the battery.
Out Of Control!!
Joined: Apr 2019
Posts: 11,923
Likes: 6,776
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
AUX batt
2014 w212
Auxiliary battery malfunction came up on dash I checked battery and had corrosion on positive side I checked volt battery has 10.3 volts I cleaned everything put back together and started car still 10.3 bolts I took positive off while still running and tested the cable alone no volts any ideas why ???
Auxiliary battery malfunction came up on dash I checked battery and had corrosion on positive side I checked volt battery has 10.3 volts I cleaned everything put back together and started car still 10.3 bolts I took positive off while still running and tested the cable alone no volts any ideas why ???
As always be careful not to short battery to GND when working with connections.
Buy a CTEK charger to prevent MAIN AGM battery drainage while parked. AUX is virtually unused while MAIN stays above 12.5V.
I wonder what type of AUX battery put out acid corrosion... is this normal vented AGM ??
Some of these 2014 chassis have a pronounced appetite for batteries - Check the voltage while driving with the cluster display to see voltage deep below 12.3V: "drain by driving". No code, no CEL
MBWorld Fanatic!
Joined: May 2021
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From: US
2008 E350, 2012 ML350, 2014 E350, 2015 ML350
and, please do NOT disconnect a battery with the engine running unless you want to replace a bunch of electronic modules. Lucky if you just blew a fuse doing that.
Read @CaliBenzDriver advice because shorting a battery, or reverse polarity when jumping can take an ECU in a flash, and a few $$$ later you might get it back to life.
Read @CaliBenzDriver advice because shorting a battery, or reverse polarity when jumping can take an ECU in a flash, and a few $$$ later you might get it back to life.
