"Auxiliary battery malfunction"
05-03-2017, 03:02 PM
#1
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E 63S Wagon Renntech, E55 Renntech, SL65, SL 55 030, ML, bunch of old ones--they come, they go...
"Auxiliary battery malfunction"
Before I buy the wrong battery, I wonder if it is the same as other 12 model 212's....this is a 12 63 US model, with a 157 and a .9. I'm a bit confused, I always thought the small battery was the starter battery and the large one controlled the other functions. Does this one control other functions--I think it controls the ECO function--or do I have it backwards? I'm thinking this is the one in the spare tire well. Sorry for the overly simple question, just haven't experienced this on a 212.....Warning message is on nearly every start now, and a two hour trip last weekend did not nothing to relieve it. In the past, the small battery almost always had to come from the dealer, and it wasn't crazy expensive...
Thanks for the help....sorry for the ignorance!
Thanks for the help....sorry for the ignorance!
05-03-2017, 05:44 PM
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2003 W211 E55, 2003 W220 S600
The small battery controls some convenience features.
It also provides supplemental power if the main battery voltage is low
It also provides supplemental power if the main battery voltage is low
Last edited by shardul; 05-03-2017 at 05:47 PM.
05-03-2017, 06:18 PM
#3
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Isn't there another auxilary battery below the dash in the area near the driver's knees? Or is that only for '10-'11 models?
05-03-2017, 07:14 PM
#4
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If you have the trunk aux battery, you don't have the small one on the left side of the dash.
The trunk battery is used in conjunction with the eco-stop logic to help maintain system voltages during engine-off situations and on re-start.
They do fail all the time, they have an internal resistance check that fails and you get the message. Usually the battery will still show 12.6+ volts and be ok, but as soon as it gets at all worn the car wants it replaced.
The trunk battery is used in conjunction with the eco-stop logic to help maintain system voltages during engine-off situations and on re-start.
They do fail all the time, they have an internal resistance check that fails and you get the message. Usually the battery will still show 12.6+ volts and be ok, but as soon as it gets at all worn the car wants it replaced.
10-18-2019, 07:38 PM
#5
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I just got the warning message "Auxiliary Battery Malfunction". I connected to my battery charger and status was not low. Do both batteries charge together?
10-31-2019, 06:45 PM
#6
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