When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Hello all, i need some help from my w212 companions, I'm having a hard time diagnosing as it seems an electrical issue, if someone is also driving a w212 E200 blue efficiency i want some voltage data to compare with, at idle with no load my voltage is 12.6v, at idle with only headlights on its 13.5v , but when idling with full load (MAX AC fan, window defogger, fog lights) the voltage is between 12.8 - 13.1 which i think is low for full load mode, please note that with full load the car lights starts to flicker and all car electronics are affected i could even hear the AC blower lowering and rising, and sometimes its not even capable of supplying sufficient electricity to run full MAX, i am suspecting either the alternator or the voltage regulator, if anyone could suggest ideas i would be grateful, i hooked up a scan tool no fault codes but the car surges badly with full load. The idling is smooth without load but with load its crappy
if you're only seeing 12.8-13.1 at idle with full load, it sounds like your alternator/regulator isn't up to snuff. does the voltage recover to 13.5 or so when you rev the engine above idle at full load?
fwiw, the USA never saw the E200 or the M271 in any form in a W212, maybe that engine was used in W203 C class or something.
if you're only seeing 12.8-13.1 at idle with full load, it sounds like your alternator/regulator isn't up to snuff. does the voltage recover to 13.5 or so when you rev the engine above idle at full load?
fwiw, the USA never saw the E200 or the M271 in any form in a W212, maybe that engine was used in W203 C class or something.
only if i rev it to 3k and above then i might get 13.5v.
if you're only seeing 12.8-13.1 at idle with full load, it sounds like your alternator/regulator isn't up to snuff. does the voltage recover to 13.5 or so when you rev the engine above idle at full load?
fwiw, the USA never saw the E200 or the M271 in any form in a W212, maybe that engine was used in W203 C class or something.
the w203 has the older version of the m271, the new m271 comes in many vehicles as the w204 and the glk as well, the specific engine model is M271.860, it has multiple voltage readings depending on load and situation its all part of the blue efficiency program but even though i think my alt or voltage regulator are under performing and i would figure the cause of this that for a period of a year i had oil leaking from the power steering reservoir into the alt and i have driving it with the leak for almost a year.
I would not jump in changing the alternator based on the information posted so far. At no point says it that battery voltage is below 12 V.
If the alternator is bad the voltage should drop below 12.5 V and as long as it does not all equipment designed to run with 12 V should work just fine. I would look into place that supply power to all “gizmos” that show “flickering” or other symptoms.
One way to easily troubleshoot this is to put a battery charger on the main battery and charge it all the way full. Then with fully charged battery you know that everything should work fine for awhile regardless of the condition of the alternator. If problems persist it is not an alternator issue.
I don’t know if this trick works the same in your car but I can pull the full charging voltage from my alternator by turning the fog light ON. My car is a 2010 E550 and fog light control is by rotating the light switch to head lights position and then pulling the knob out. This makes battery voltage to about 14.5 V regardless of driving or on idle.
If you can get your voltage to above 14 V you definitely have no alternator problem. Based on it giving 13.5 V for me already says there is no alternator problem. Voltage at the battery must be going below rated value before you can say alternator is bad. If it stays above 12.5 with all load ON the issue is somewhere else.
I would not jump in changing the alternator based on the information posted so far. At no point says it that battery voltage is below 12 V.
If the alternator is bad the voltage should drop below 12.5 V and as long as it does not all equipment designed to run with 12 V should work just fine. I would look into place that supply power to all “gizmos” that show “flickering” or other symptoms.
One way to easily troubleshoot this is to put a battery charger on the main battery and charge it all the way full. Then with fully charged battery you know that everything should work fine for awhile regardless of the condition of the alternator. If problems persist it is not an alternator issue.
I don’t know if this trick works the same in your car but I can pull the full charging voltage from my alternator by turning the fog light ON. My car is a 2010 E550 and fog light control is by rotating the light switch to head lights position and then pulling the knob out. This makes battery voltage to about 14.5 V regardless of driving or on idle.
If you can get your voltage to above 14 V you definitely have no alternator problem. Based on it giving 13.5 V for me already says there is no alternator problem. Voltage at the battery must be going below rated value before you can say alternator is bad. If it stays above 12.5 with all load ON the issue is somewhere else.
okay what i did was i fully charged the battery the other day using a battery charger and honestly it did stop the symptoms for a couple of days, and then it started again, also today i placed the car on full load with every electrical thing on and max ac blower the voltage dropped up tp 12.3v and after a while the AC blower Fan speed lowered alot by its own, i had to turn off the headlights for it to regain power again, i even revved the engine up to 3k and it did not raise the voltage, the weird thing is that this voltage issue isn't constant but actually intermittent at first the car starts fine and outputs good voltage but after 30 mins or so from driving the voltage starts to drop once again, and believe me when i say everything was affected. And if i drove the car with only partial load like only headlights without AC, or with AC without headlights it drives fine. I've read a comment posted in 2013 by a fanatic member i dont recall his name but what he said that on the blueeficieny w212 m271 engine with full load on the voltage should be above 14v but thats not happening in my case unfortunately. Plus I've already scanned the car using an obd reader and got no fault codes.
I would not jump in changing the alternator based on the information posted so far. At no point says it that battery voltage is below 12 V.
If the alternator is bad the voltage should drop below 12.5 V and as long as it does not all equipment designed to run with 12 V should work just fine. I would look into place that supply power to all “gizmos” that show “flickering” or other symptoms.
One way to easily troubleshoot this is to put a battery charger on the main battery and charge it all the way full. Then with fully charged battery you know that everything should work fine for awhile regardless of the condition of the alternator. If problems persist it is not an alternator issue.
I don’t know if this trick works the same in your car but I can pull the full charging voltage from my alternator by turning the fog light ON. My car is a 2010 E550 and fog light control is by rotating the light switch to head lights position and then pulling the knob out. This makes battery voltage to about 14.5 V regardless of driving or on idle.
If you can get your voltage to above 14 V you definitely have no alternator problem. Based on it giving 13.5 V for me already says there is no alternator problem. Voltage at the battery must be going below rated value before you can say alternator is bad. If it stays above 12.5 with all load ON the issue is somewhere else.
and regarding the part about the 14v, i could barely get 13v at some times most of the time if I'm lucky with full load its like 12.8 or 12.7, and at the moments of flickering the voltage is around 12.3 or 12.2v with full load. Plus when i say flickering i mean everything is flickering (Blower Motor, Headlights, cabin lights, ambient light, exterior license plate light, door panel lights, drawer lights, instrument cluster backlight literally every electrical thing is flickering).
The issue with these "smart" charging systems is diagnosis is not as simple as older voltage regulated systems... now you have computers determining how to charge the battery and to what state. I think without access or diagnosis using MB Star diag, like Xentry... were to go?
To me it sounds like a control issue if indeed the charging voltage is too low...
and regarding the part about the 14v, i could barely get 13v at some times most of the time if I'm lucky with full load its like 12.8 or 12.7, and at the moments of flickering the voltage is around 12.3 or 12.2v with full load. Plus when i say flickering i mean everything is flickering (Blower Motor, Headlights, cabin lights, ambient light, exterior license plate light, door panel lights, drawer lights, instrument cluster backlight literally every electrical thing is flickering).
Again, if voltage is above 12 the systems should work.
How do you check the voltage? If you measure from battery cable, like the positive you probably do you could have a simple problem as the loose battery cable. This would give you charging voltage but battery could be lower if connection is bad and only partial current flow to battery takes place.
The issue with these "smart" charging systems is diagnosis is not as simple as older voltage regulated systems... now you have computers determining how to charge the battery and to what state. I think without access or diagnosis using MB Star diag, like Xentry... were to go?
To me it sounds like a control issue...
already tried that, brought it to a car diagnosis specialist he scanned it with the mb star and found nothing, and to what i assume is that the alternator is controlled via the rear sam, the only fault code found on the rear sam was low battery voltage fault and nothing else.
Again, if voltage is above 12 the systems should work.
How do you check the voltage? If you measure from battery cable, like the positive you probably do you could have a simple problem as the loose battery cable. This would give you charging voltage but battery could be lower if connection is bad and only partial current flow to battery takes place.
i tried measuring it from different places using a multimeter and also got a reading via the engineering menu all gave me the same readings, plus all battery cables and ground points have been checked they're all good.
Again, if voltage is above 12 the systems should work.
How do you check the voltage? If you measure from battery cable, like the positive you probably do you could have a simple problem as the loose battery cable. This would give you charging voltage but battery could be lower if connection is bad and only partial current flow to battery takes place.
I guess we should define "work"? As one of the strategies MB has is to shutdown convenience features when onboard voltage drops below a certain threshold. I'll have to dig up some material on it, because off hand I can't remember. Another thing to consider is he has a "blue efficiency" model, which I believe has even further measures related to efficiency (thus strategies might be different). So I would just be cautious correlating our experience on US model cars.
already tried that, brought it to a car diagnosis specialist he scanned it with the mb star and found nothing, and to what i assume is that the alternator is controlled via the rear sam, the only fault code found on the rear sam was low battery voltage fault and nothing else.
Okay, no faults... but there's more data in there that could help diagnose the issue. For one, I'd be curious to know if one could monitor energy management. Essentially seeing when the car commands the alternator to charge and then measuring the output confirming whether it does.
I guess we should define "work"? As one of the strategies MB has is to shutdown convenience features when onboard voltage drops below a certain threshold. I'll have to dig up some material on it, because off hand I can't remember. Another thing to consider is he has a "blue efficiency" model, which I believe has even further measures related to efficiency (thus strategies might be different). So I would just be cautious correlating our experience on US model cars.
As ausmbtech stated a couple of years ago that the battery voltage with full load should be around 14 - 14.6.
Okay, no faults... but there's more data in there that could help diagnose the issue. For one, I'd be curious to know if one could monitor energy management. Essentially seeing when the car commands the alternator to charge and then measuring the output confirming whether it does.
What did the specialist recommend?
he sure did not perform such a test, and honestly i didn't even know that this could be achievable with a mb star tool, I'll sure return to him to try this test.
Okay, no faults... but there's more data in there that could help diagnose the issue. For one, I'd be curious to know if one could monitor energy management. Essentially seeing when the car commands the alternator to charge and then measuring the output confirming whether it does.
What did the specialist recommend?
if this is possible for sure it'll make my life a bit easier.
I really like this stuff... but its an exercise in mental-masturbation at some point. At the end of the day, unless someone has has the EXACT same issue... I don't think you or even many of us, have ALL the tools and INFORMATION (Mercedes technical) to provide exact fix.
Can you post your VIN, maybe I can pull some docs out of WIS.
I really like this stuff... but its an exercise in mental-masturbation at some point. At the end of the day, unless someone has has the EXACT same issue... I don't think you or even many of us, have ALL the tools and INFORMATION (Mercedes technical) to provide exact fix.
Can you post your VIN, maybe I can pull some docs out of WIS.
Hahahah yeah, i am having a hard time diagnosing this issue, the dealership in my country is crap as well as the specialists they're light years behind, my vin is WDDHF4JB6AA165321, but honestly I'm 90 percent suspecting the alternator because the way it behaves it doesn't fit the criteria of a control issue nor an electrical connection issue, when the car is fully warmed and under load thats when the issue appears, plus i dont have an idling issue nor misfires, and from what i know is that the rear sam is the module giving alt commands through COM wire and if the rear SAM is faulty I'll get some fault codes in addition to other parts acting up as well but the issue is related to a hot engine which fits the criteria of a faulty alt, i am really considering replacing the alt, i found a new valeo alt online for 260 bucks.
its really unfortunate that the blue efficiency m271 engine isn't common in the US, you guys are the best at solving such complex issues.
My '12 E350 4matic has blue efficiency badges on both front fenders, I think this was just acknowledgment of an upgrade to the charging system. I would also imagine the newer 212"s had the same with yearly upgrades to improve this system
It seems my "13 Charges at Idle and my '12 does not.
if the voltage isn't at least 0.8 to 1.2V higher than the battery's at rest voltage, which is 12.6V when its fully charged, then your cars electrics will be pulling power from the battery instead of from the alternator. with a fully charged battery, if the charger (alternator) is at about 13.5V, then there's no current going into the battery, all the current would be going into the vehicle electric systems (lights, ignition, fuel injection, etc)
Agree with BMW. MB own "smart" charging algorithm is confusion contribution to troubleshoot if based on alternator voltage only.
Mine has the Hyundai Mobius sensor at the battery negative terminal, this is part of the smart charging management. This stuff surely also is a current sensor ( shunt/CT). https://www.ebay.com/itm/Mercedes-E-...-/143208340324 2nd photo
30 minutes charging profile below. Anything 12.5V and lower = discharge on purpose by MB algorithm. 12.7V above is charging.
Also agree with OP, too much deficit at hot temperature of alternator is sign of a "weakening" alternator.
Try to unplug the Mobius sensor at battery negative terminal, see if that can allow conventional charging "un-smart" of the alternator ?
03-06-2021, 03:45 PM
