e500slr

Hey guys,

My W212 M156 E63 is giving me a battery logo (not auxiliary) and then after a while it will turn on the ESP, ABS lights and then turn off.

I think the alternator is not charging the battery.

When I put a charged battery in there it starts again but then does the same thing.

It's as if the car is running off the battery and the alternator not charging it.

Could it be something else though, should I get the car scanned?

I have a spare alternator but it seems like a ***** to get to and replace. It's so tight in there.

Thanks for any help guys.

Celicasaur

Seems like you already know the deal mayn.

I'd only add that to confirm the alternator, you probably would want to stick a multimeter on the battery terminals with the engine running....if you're not seeing 14V+ while idling, then you'll now to block out next weekend to swap out that alternator

e500slr

I was thinking obviously it's the alternator but knowing these cars have alot of control modules so I thought maybe just maybe it's a battery control module or something.

I'll do what you said though to try and confirm it.

Celicasaur

You're correct to wonder if it's a battery control module tbh. I had a W211 E55 and know all about the troublesome electrical system on that car

However I think (somebody correct me if I'm wrong here) to easily identify a faulty module, you really need a Mercedes Star/Xentry computer and that will tell you everything in one hit.

Perhaps...if you're doing good for time...you could remove the alternator and take it to a local refurb specialist. They'll be able to 1) tell you if the alternator needs a rebuild or if the brush packs need replacing or whatever...who knows mayn. Only one way to find out. Keep us posted

dinman

pretty similar thing happened on my 2010 e63 like two years ago. Replaced the voltage regulator and all is good

e500slr

Where is that exactly?

dinman

Located on the back of the alternator. It can be accessed with the alternator still in the car

Celicasaur

Din, that's the thing with the carbon brushes, right? They wear out over time....? Or was this a mini module as such?

dinman

brushes, correct. here was my old one vs the new one at 103k miles. i was getting very inconsistent voltage readings. anywhere from 8v-15v at the battery while driving. obviously it smacked the battery, so after replacing the voltage regulator i got a new battery too.

to the OP- mine did the same stuff. abs lights, COMAND shutting down, etc. voltage regulator is only ~$120. It's worth a shot vs buying an alternator IMO. Get the car in the air, i believe remove the underbelly pans, remove the cover on the back of the alternator, and there it is.

e500slr

Thanks so much for the info. That's exactly what I'm getting. I'm definitely going to try that. Hopefully this will fix it. I just chewed my rear right brake line too for whatever reason so I have to bleed and flush the whole system, replace the hose and make sure it doesn't happen again. This week has not been a good week for my car

e500slr

Knock on wood...because of my luck but what you suggested worked Dinman, thank you so much, it was a PAIN IN THE @RSE but changing the alternator would have been a 1000x worse. Thank you Dinman and Celicasaur for the input and help.

I could immediately see the problem by the way, it was the brushes, they were absolutely destroyed, the spring was getting stuck too explaining why it would sometimes work and sometimes not.

Celicasaur

Ahhh great news bro.

Part number?

I might do mine also then as preventative maintenance. Been getting a couple of flat batteries lately. Will be nice to keep the car at full health where possible.

e500slr

Sorry for the late reply, the part number for mine at least is F00M346080.

Usually when this problem happens it's not just a flat battery, you actually get a red big battery logo (not auxiliary) on the cluster and there won't be the normal 13.7-14.1 volts at the battery leads when the car is on. It will eventually shut off whole running since there is no power to run the spark and engine ECU etc as there is no alternator. I was in a car park and mine actually shut off the cluster and everything while the car kept running AND GET THIS, I turned it off by removing the key from the ignition AND IT STAYED ON!!! I popped the bonnet and took off the battery lead to turn it off, it wasn't responding at all and there gearbox wasn't working. Luckily I had another charged battery, put it in, drove home as I wasn't far and changed out that part which was a BIATCH but it worked. I was also getting an auxiliary battery message, probably unrelated but I have a spare one so I swapped that too.