Auxiliary Battery Malfunction!
Thread Starter
Member
Joined: Oct 2009
Posts: 99
Likes: 22
From: New York
2020 GLE450 polar white AMG pkg.
Auxiliary Battery Malfunction!
Just wanted to pass this along....for those of you who don't cancel the ECO function. Should your Aux Battery run down....WARNING - when the engine attempts to restart say after a traffic stop, you will experience what feels like a rear end collision! In my case, the engine restarted and the car leaped forward with a BANG and almost felt like the rear end fell out! So after some research I discovered the AUX battery is primarily used as a starting battery after a normal ECO shutdown. At this point the ECO function should also disable (cannot turn on or off). Later on i finally got the message "aux battery malfunction" Luckily I had my MB dealer replace the battery (under warranty) and all is good. If you experience any unusual roughness when the engine restarts on ECO, these are definite warning signs to replace the aux battery soon!
Senior Member
Joined: Sep 2002
Posts: 352
Likes: 12
From: Worcester, MA
15' CLS400
I know this is a year old thread by I just got this same message although I didn't have any rough starts or anything. Everything has been working fine until today I started getting this message upon starting the car, and I did notice the car wasn't taking advantage of ECO mode... So I just hooked up my charger to it to see if i could give it a little charge and my charger read 13.7v saying its at 96% charged. What gives? I suppose the error could be from a loose wire.. anything else?
Last edited by TechSuperstar; Dec 31, 2018 at 04:58 PM.
Senior Member
Joined: Sep 2002
Posts: 352
Likes: 12
From: Worcester, MA
15' CLS400
MBWorld Fanatic!
Joined: Sep 2018
Posts: 3,244
Likes: 933
From: New Orleans Area
2015 E400 Sedan
Senior Member
Joined: Sep 2002
Posts: 352
Likes: 12
From: Worcester, MA
15' CLS400
Ok, disconnected and tested. Still reading up around 14v. I put it on my charger which only charged for 5min before the charger said it was fully charged. Could there be other causes for the malfunction message? Just don't want to spend the money for a battery and find out its not the issue.
MBWorld Fanatic!
Joined: Sep 2018
Posts: 3,244
Likes: 933
From: New Orleans Area
2015 E400 Sedan
Ok, disconnected and tested. Still reading up around 14v. I put it on my charger which only charged for 5min before the charger said it was fully charged. Could there be other causes for the malfunction message? Just don't want to spend the money for a battery and find out its not the issue.
Maybe battery had a bad day from sitting too long?
I would remove battery and have load tested at auto parts store?
They have replacemnts for about $100.
there is thread about some relay or something that prevets aux battery from properly charging but it is rare.
Wehn mine went bad (warranty) both dealers checked the charging system to the aux battery and said ok.
My guess is original battery sat so long before car was sold it died.
Then first dealer replaces with bad battery which happens way more then people think.
Trending Topics
Senior Member
Joined: Sep 2002
Posts: 352
Likes: 12
From: Worcester, MA
15' CLS400
Ended up going to my local "Batteries Plus" store. Sure enough it read 14v on their tester but failed the load test. Ended up paying $112 for a Duracell Ultra, part # CYL10001 which fit perfect. No more error. Note: The dealer wanted over $300!
MB World Stories
The Best of Mercedes & AMG
Manual Mercedes? 6 Times Sindelfingen Let Drivers Have All The Fun
Verdad Gallardo
Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren
Verdad Gallardo
8 Classic Boxy Mercedes Designs That Have Aged Like Fine Wine
Verdad Gallardo
Flawlessly Restored Mercedes 190E Evo II Heads to Auction
Verdad Gallardo
Electric Mercedes C-Class Unveiled: 11 Things You Need to Know
Verdad Gallardo
Mercedes EQS Gets A Major Update: Everything You Need to Know
Verdad Gallardo
5 Underrated Mercedes-Benz Models That Don't Get the Love They Deserve
Verdad Gallardo
Mercedes 300D Has Pushed Well Past 1 Million Miles and It Ain't Stopping
Verdad Gallardo
