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Hello everyone,
I ve been experiencing some electrical issues lately. Let me recap where I am to see if it helps and if anyone has the same. I’ll update once it ll be completely fixed.
The Battery sign started to came up on my car.
At first, we believed it was the main battery that was weak. Got it replaced for an insane amount of money (they charged a lot of diagnostic )
3Km after leaving the dealership the light came back.
I went back. More diagnostic charged… and they said Alternator to be replaced… Warning
since I don’t like to pay twice for service that is not properly given, i went to another mechanic to do the job.
we replaced to alternator since it was the official and very expensive diagnostic from the dealership.
Guess what?
We got the message again!
Then I decided to run my own little analysis. I used the “secret mode” to follow the voltage variations. Engine not running: 12.2V. Running normally 14.4V (At the very beginning it’s a bit less).
But, sometimes, I see a big drop to 12.2 and less while the engine is running. That’s the drop that generates the battery warning.
Trying to understand what was the cause of the drop, I tried a lot things (command, music, lights etc…) to realize that it was simply and only when the radiator fan was running.
I did not have time to look for mis plugged stuff or anything else causing a short circuit. I’ll show my car to the mechanic next week.
But before, did anyone had any similar experience?
What else that the fan could be involved? A captor?
Appreciate the help and will keep you posted.
Last edited by StLouisParis; Nov 25, 2021 at 12:47 PM.
My relative has the same problem..he had the wrong alternator at first..he has 2012 s550 4matic turbo..with the turbo you need a 220amp alternator.. no one seemed to have this alternator but the dealer. He gets the alternator from the dealer and the same ( battery not charging) comes up.. I used my scanners (autel im608 and c6 xentry) nothing comes up to rid that red sign on the dash..both scanners show both battery is charging. Found something online that was saying a software update is needed. He rides around with no issues.. but it sounds like your situation is caused by a short to power maybe caused by your fan..but let us know if you fix the situation.
My relative has the same problem..he had the wrong alternator at first..he has 2012 s550 4matic turbo..with the turbo you need a 220amp alternator.. no one seemed to have this alternator but the dealer. He gets the alternator from the dealer and the same ( battery not charging) comes up.. I used my scanners (autel im608 and c6 xentry) nothing comes up to rid that red sign on the dash..both scanners show both battery is charging. Found something online that was saying a software update is needed. He rides around with no issues.. but it sounds like your situation is caused by a short to power maybe caused by your fan..but let us know if you fix the situation.
thanks for sharing.
in my case, it shows a spike and then the alternator is cut off. So looks like a short circuit somewhere. I noticed a correlation with the cooling system when the fan is switching on. I’ll go the mechanic on Monday.
Yea..shop claimed the battery needed to be programmed... but I didn't believe him.. because these batteries dont need that.. i believe he just didn't want to tell me..🤷♂️
this is the same issues two others asked about inside the last month
do both of you have facelift cars ? (aka one's built after oct 2009),
there is no battery programming on this model (it is a normal thing on many brands today) - and std for a BMW car since forever - it allows the alternator to optimise its charging algorithm to suit the type of and ampage of the new battery - so it lasts longer and operates better
if you find the other posts - its the expensive bit you don't want to buy ( its not the batteries or the alternator ) and its a standard fault on facelift cars
My relative was told his car is a facelift car. He has a 2012 s550 4matic. We both hadn't heard of that until a mechanic told him. Battery being programmed is what he told him..
My relative was told his car is a facelift car. He has a 2012 s550 4matic. We both hadn't heard of that until a mechanic told him. Battery being programmed is what he told him..
I guess its possible - But I'd expect we'd have heard on this forum that Merc went there on this later model - on another forum full of experienced old boys, they claim only one OLD merc model ever had that battery coding feature - And XENTRY should lead anyone there if that's the fix
the indy with these Merc diagnostics I used to go to was getting nowhere on a facelift car with the fault - and in the end was throwing parts at it and scratching his head
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