Cozzi

Hi everyone, I've just registered.
I bought a 2019 W222 LWB in December 2021 and everything was fine until August this year since when I've been beset with all sort of electrical problems. As someone is the wrong side of 66, will somebody please advise me where/how the best place is on this forum for me to list the issues in the hope that someone can help with a diagnosis?
Paul
Doncaster
UK

Clk_master

hello. I have the WIS and EPC software i can help you with some schematics

MJ50

moved to W222 forum...

Sactownmb

Hello Cozzi, this is the place. Lots of helpful, experienced people here. 😎

SilberGrau57

Rodents setting up shop and chewing the wiring, or Water collecting in the electronic bay maybe due to clogged drains?

cfmistry

Electrical issues are not common on the w222. I am sorry for your experience. The first step would be to make sure to that both your main and auxiliary batteries are functioning properly.

Cozzi

You are spot-on with your suggestions, and here's what actually happened..........!!!!!

Last week as the 'starter Battery Critical' messages continued to appear with even more grim regularity and I was still racking my brains and trying to apply some element of logic to the ongoing problem, when I stumbled across a thread which described how excessive heat is the enemy of lead acid batteries. Now this got me thinking????......
It was the 19th July here in the UK when I was out in the car in middle of the day when the mercury hit over 40 degrees C. When I got home an hour later, I put the VERY hot car in the garage and shut the door. When I went back in about 30 minutes later, the heat was indescribable through a combination of 40 degrees C ambient temperature plus an engine at 90 degrees C. It must have been around 70 degrees C in there! Factor-in that the battery is situated above the tailpipes, with the benefit of hindsight it becomes obvious now that the battery was going to be toast.

I don't think I used it much until I took it out w/c11/08during the second heatwave which was then when I started to get the warnings, though now I reckon it was finished in July and the only reason I hadn't had a warning before is because it had been on the CTEK charger ever since and before I set off, so it was as 'fully charged' as it could be under the circumstances, but that didn't last long as the damage had caused it to either - only charge up so far as to 'fool' the CTEK charger and the Merc technician's software, and lose whatever little charge it actually had very quickly, or both!

When the Mercedes mobile technician came out last week for the 3rd time, we started to piece together the jigsaw and given the back story, he concluded that the starter battery was more than likely finished and needed replacing.....even though "computer says no!".............he was right!

I asked him why the Mercedes software (including that at the main dealership) couldn't spot it and he said that it's impossible for the equipment to diagnose a battery which has intermittent faults where probably some of the internal AGM cells are "shorting-out". Not surprisingly being in the U.K., he had never seen battery damage which had been caused through excessively high temperatures, as the circumstances which knackered mine were almost unique and unprecedented.

Based on my experience given all the weird warnings I was receiving both via the Mercedes Me app ('12 starter battery critical' messages) and the dashboard (varied from 'fault don't drive more than 50mph', 'starter battery critical', residual heat shutting off after 2 minutes etc), it may be worth back-tracking to see if your battery could have been heat-damaged somehow as mine was only 3 years-old.

I hope that my story will at least help someone from pulling their hair out for 3 months. My problem is now solved completely thankfully.

Mitch Alsup

This has been known since 1923..........BTW

Why would Merc (or any other car manufacture) put diagnostic SW in a car that prevented trips to the local dealer ??

Answer that question, and you will have your answer......

Cozzi

And there it is ladies and gentlemen!............
Thank you so much for going the extra mile and trying to embarrass me for having the naivity and audacity to ever consider posting in the first place. I was wondering how long it would take before someone couldn't help themselves. Though having thought about it, that type of person has been known since 1923 BTW. In hindsight, I guess I really should have known better. I'm now going to do a deep dive into the finer points of lead acid batteries to prevent me ever ever having the nerve to post in the future. I'll also while I'm at it, do the same on ion-lithium because at some point in the future I'll be driving a car with one in it. This will then allow me to potentially help some poor sod who has had three months of exasperation and head-scratching, as opposed to a 'look at me everyone, I'm VERY knowledgeable, and need your validation" reply. In summary, your comments and underlying arrogance are neither welcome nor appreciated, and I would suggest your time and effort is better served having a good look at yourself before subject others to your unnecessary and completely irrelevant responses. If your previous responses and posts have been in this vein, I'm surprised that you have been tolerated and allowed to remain a member.