Auxilary Battery Malfunction Fault Codes

Justintyme

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Mercedes Benz w212 E Class
While removing the towbar from my 2014 w212, I had to disconnect the cable supplying the power to the trailer relay. Now its reconnected, but showing the " Auxiliary Battery Malfunction", and showing the following codes, C073300 and A1DC01. I cleared the codes with the iCarsoft CR Pro, and after restarting it was fine no dash warning, but after a few moments, it came on again. Any suggestion's please? I've see a few videos on the net showing battery's being replaced without issue, so wondering where I went wrong.
 

KillerHERTZ

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Give it a good run, its possible that the Aux battery is on its way out but just needs a top up.
 
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Justintyme

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Give it a good run, its possible that the Aux battery is on its way out but just needs a top up.
Thanks for your reply Killer HERTZ, The Auxiliary battery is exactly 2 years old, because when I bought the car 18 August 2020, they had to replace it. And no problems since then. See pic where it shows the exact connection I used to take a live feed for the towbar when I was fitting it, also 2 years ago. If I had my time back again, I'd have just snipped the cable right at the joint, instead of undoing the main cable to remove the trailer feed wire. It was only seconds disconnected, but with electrics, seconds may as well be hours or days... any info to be gleaned from the codes, A1DC01 and C073300 ?


MB Auxiliary Battery Connection Used 20220801_124231[4295].jpg
 

Diesel Benz

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Feb 3, 2006
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223.168 & 213.012 & 906.633
While removing the towbar from my 2014 w212, I had to disconnect the cable supplying the power to the trailer relay. Now its reconnected, but showing the " Auxiliary Battery Malfunction", and showing the following codes, C073300 and A1DC01. I cleared the codes with the iCarsoft CR Pro, and after restarting it was fine no dash warning, but after a few moments, it came on again. Any suggestion's please? I've see a few videos on the net showing battery's being replaced without issue, so wondering where I went wrong.

What does iCarsoft tell for these codes? Which control unit did they come from? I had a quick look at Star but could not find a control unit that these codes were assigned for. Need to read the list control unit by control unit and I gave up after the most obvious ones.
 
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Justintyme

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Mercedes Benz w212 E Class
What does iCarsoft tell for these codes? Which control unit did they come from? I had a quick look at Star but could not find a control unit that these codes were assigned for. Need to read the list control unit by control unit and I gave up after the most obvious ones.
Hi Diesel Benz, thanks for trying to help. I checked again yesterday evening, and two codes appear normal, that is they appear under the "U" prefix. They are :-
U010300. "State Historic. Communicator selector lever module has a malfunction."
U103888. "Diagnostic CAN has a malfunction BUS off."
U103811. " The Diagnostic Communicator has a malfunction, There is a short to ground"
U118300." The diagnostic CAN network management is unstable".
P061000 " The coding of the control module is incorrect."
C073300, "Read fault memory of control module. "N10 ( SAM Control Module)"
A1DC01, " State Current. The buffer battery for the ignition lock has a malfunction."
913095, " "Parktronic sensor 8 has a malfunction . The mechanical set up is not OK. " (This could refer to the sensor which came adrift when I was removing the rear bumper, and I had to glue it back in place,)
What's not working either is the brake hold when I double press the brake pedal. I found that out when stopped in traffic facing down hill, or the ECO .
I've just driven it 50 miles or so, and I thought that the battery had sufficient charge, and so it seemed because the " Auxiliary Battery has a malfunction stays off, and the green ECO icon comes on". But it was short lived, after a few mins, it comes back on again. I think that I will put the battery on a slow trickle charge overnight, and see if that will make ant difference. Its more in hope than certainty though ..50 mile drive should have brought it back to full, I think. I wonder what the specs are for the battery in a 2014 w212 E class 220.? and can they die as quickly as that???
Thanks again Diesel Benz fir your help, Its appreciated, JIm.
 
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Justintyme

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Give it a good run, its possible that the Aux battery is on its way out but just needs a top up.
Gave it a 50 mile spin this morning KillerHERTZ, and it seemed to work...turn on the ignition, start the car, and the green ECO light was on, and the malfunction aux batter warning was off ( but still no "Brake On" after pressing the brake pedal twice) but a few mins later, AUX Malfunctioning was back on.. Looks like a new battery is needed.....what surprises me is that how quick it went, considering it was only in the car 2 years.. but TBH, it name does not fill me with confidence " Rocket Power Battery"....:rolleyes:o_O
 

Smiley

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Are you sure that the battery that was put in two years ago was a brand new battery - if it was put in by someone to sell the car they may have pinched it from another car?
 
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Justintyme

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Yes Smiley, that's a very good point !!! The SIL who is a commuter engineer, went through the the iCarsoft CR Pro data' S s, and did some investigating himself. Seems that all the codes thrown were linked to the battery. So now its in the garage.
 

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