W221 s350 bluetec red battery light / no charging

Botus

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I was at an indie in the spring, some bloke with 2011 or 2012 a v8 turbo w221 had just fitted a main battery to fix same issue.... it didn't help. Put on STAR and decided the other battery was at fault. Fitted genuine Merc second battery fault still present.

After much scratching of heads they decided it was control module at fault...
 
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alex_78

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I was at an indie in the spring, some bloke with 2011 or 2012 a v8 turbo w221 had just fitted a main battery to fix same issue.... it didn't help. Put on STAR and decided the other battery was at fault. Fitted genuine Merc second battery fault still present.

After much scratching of heads they decided it was control module at fault...

do you mean control module in battery clamp?
 
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alex_78

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right no so happy today
so far car was playing with no charging after long drive and engine switch off then on again but today don't want to charge at all...
starts ok then on board voltage monitor show discharging roughly -30A and voltage 11.4v (confirm it with manual meter on battery itself) so i guess either battery is to bad (even if starts car ok) or this control module on clap i think...

battery is probably from new so is old so i replace it tomorrow and hopefully that make trick if not it will be not so good news just before my holiday...:mad:
 
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alex_78

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also im wondering if i fit new battery do i need to reset this battery sensor? according to John youtube clip sensor can remember old battery voltage and if you charge it should be not charged directly to battery so is interesting how sensor act with new battery fitted... questions questions....
 
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alex_78

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well i bought battery fit it and same problem nothing change at all

start car and on dash monitor show discharging on beginning from over 100A which settle on -30A
i take car for small spin (on youtube clip it says that battery sensor read data after 100meters still no luck
i think i drove around one mile, don't want to go to far in case i have 2 tonne tank without power supply stuck somewhere)

i have advanced scanner for merc which make most of star function nothing related to charging was discovered

i need car working coz of my holiday soon and now i think start digging to alternator is only option

earlier this week was most of the time charging, then yesterday and today no charging at all

is anything what i can check like fuses etc?

what is easiest access on om642 to alternator to check is charging on output?

is weird coz it was no whining noise or any other alternator normal warning symptoms so maybe is regulator or just something small what i missed ?

now before holiday price for new alternator is not very welcomed so i hope it can be fixed somehow any suggestion more than welcomed
 

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If no other suggestions are forthcoming you may have to bite the bullet and get to a specialist like Klasse to investigate fully, sorry!
 

mioba

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Get a voltmeter across the battery when engine running. This will soon tell you if the alt is working or not. Seems like it isn’t. Should read about 14v.
Then switch of engine and the v should drop.
Old school basics mate.
Failing that seems like a bad connection somewhere or alt fault.
 
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alex_78

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If no other suggestions are forthcoming you may have to bite the bullet and get to a specialist like Klasse to investigate fully, sorry!
if you suggest the same Klasse which i think then sorry i was ripped off by them big time, charge me a lot and don't fix issue, they clearly was one of the reasons i start work on car myself and don't care about service log but have job done properly....

i succeed myself with oil cooler seals, boot amp, few regular services (oil filters), bluetec issues, brake service and more

Klasse fail to fix clunk in suspension and they claim to be professionals (yes they are in charge nearly the same as dealer) they replace wrong parts (im sure they happy with their margin on parts plus labour rate) but fix of clunk was cheap an easy if someone know what to do but for Klasse it was better to rip me off and end up on one occasion...

clunks problem with suspension i fix myself (me amateur self learner)

but now with my tools and scanner im ok to make most things myself obviously with forum/youtube help....

so with all respect i can't recommend klasse at all, they friendly and maybe ok to change oil etc or coz of friendly approach they can be ok with "blonde" customers who like to pay extra for everything, but more complex problems or more unusual models they are useless...
sorry!
 
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alex_78

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Get a voltmeter across the battery when engine running. This will soon tell you if the alt is working or not. Seems like it isn’t. Should read about 14v.
Then switch of engine and the v should drop.
Old school basics mate.
Failing that seems like a bad connection somewhere or alt fault.

thats my plan and for that reason i was asking what is easiest access to alternator before i remove to many parts to get voltage reading coz on battery is clearly not charging...

also i think about some electronic glitch coz it was working ok then stop then ok then stop so it not looks like mechanical failure more like relay, sensor, voltage regulator etc ok tomorrow morning car go on ramp and i get my hands dirty ;)
 

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if you suggest the same Klasse which i think then sorry i was ripped off by them big time, charge me a lot and don't fix issue, they clearly was one of the reasons i start work on car myself and don't care about service log but have job done properly....

i succeed myself with oil cooler seals, boot amp, few regular services (oil filters), bluetec issues, brake service and more

Klasse fail to fix clunk in suspension and they claim to be professionals (yes they are in charge nearly the same as dealer) they replace wrong parts (im sure they happy with their margin on parts plus labour rate) but fix of clunk was cheap an easy if someone know what to do but for Klasse it was better to rip me off and end up on one occasion...

clunks problem with suspension i fix myself (me amateur self learner)

but now with my tools and scanner im ok to make most things myself obviously with forum/youtube help....

so with all respect i can't recommend klasse at all, they friendly and maybe ok to change oil etc or coz of friendly approach they can be ok with "blonde" customers who like to pay extra for everything, but more complex problems or more unusual models they are useless...
sorry!
Thanks for the review Alex - doesn’t sound good at all then!
 
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alex_78

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Thanks for the review Alex - doesn’t sound good at all then!
they are ok to change oil and give you free valet but that's it.

i'm kind of happy about that experience with them coz i always want to learn about cars and that was final touch. in past i made some timing belts and services on my previous cars etc but not that advanced as w221 but with time and more jobs completed i feel more confident and that best bonus of this situation.

now is not only about saving money but also i know i done job right and that make you feel safe and happy at least it is me ;)
 

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thats my plan and for that reason i was asking what is easiest access to alternator before i remove to many parts to get voltage reading coz on battery is clearly not charging...

also i think about some electronic glitch coz it was working ok then stop then ok then stop so it not looks like mechanical failure more like relay, sensor, voltage regulator etc ok tomorrow morning car go on ramp and i get my hands dirty ;)


to test the battery with a voltmeter as my post you don't need to access the alt just yet. put the voltmeter across the battery terminals.

god luck, let us know how you do get on.
 
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alex_78

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to test the battery with a voltmeter as my post you don't need to access the alt just yet. put the voltmeter across the battery terminals.

god luck, let us know how you do get on.

done that before and is no charging on battery (same after fit new battery)

now i need access to alternator to check is charging on output if so it will be cable if not it will be alternator or some sensor which switch alternator on, also i was reading about problem with roller clutch on alternator so going under car is only option...
 
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alex_78

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after thinking and make some research i find out that more likely my alternator can have faulty voltage regulator (it was some series of them very common for failure) with my luck i have almost all common faults with my car i decide to replace it.
i have new battery now i get new alternator, i want to keep car anyway for a while so i think is good investment.

right so far car is on ramp, removed some plastic underneath some plastic on top and ribbed bet, have visual contact with "suspect"
is only 2 things which im not sure:

-om642 is alternator water or oil cooled or none? do i need drain any of this systems

-after realese 4 bolts is better to take it up or down so far looks like is to big either way so any advice what to remove first to make removal of alternator straight forward?
 
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alex_78

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mission accomplished - old alternator out
now waiting time for new part and hopefully that fix the issue....
 
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alex_78

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What a saturday, on the morning quick drive to pickup parts then work on car again.

New alternator fitted at same time new belt and turbo and air filter seals result???
Just look at picture

Thanks to all of you for your time and suggestion

And BIG special thanks to guys from Mercedes Grangemouth Parts Dep for club discount and really quick delivery
Really recommend them and from now on it will be place where i will buy my parts

Thanks again and have a great weekend everybody

Ps as explained in video this charging voltage and amperage changing dynamicly so current reading is high but after some time it goes lower

Im really happy with result
 

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