wjcandee

Seawind: It sounds from your additional explanations like you are in fact doing all the basics properly. On the Advance alternator, I'm guessing that in fact whatever voltage regulator that Advance sells separately is not the voltage regulator used in the remanufactured alternator, but that shows how thorough you are being in your thinking.

Advance is going to buy alternators from a national remanufacturer. Actually, on the one for your car, they appear to use two remanufacturers. One of those may in fact be Quality Built, and those are recognized as excellent remanufactured alternators. Don't know who the other is, perhaps Delco Remy, perhaps someone else. And these remanufacturers are going to use whatever parts in your alternator that they usually use; not necessarily the ones sold separately at Advance. There is a remote chance that you got a bad unit; they do sneak through (less with QB because they test them thoroughly and replace all the wear parts whether they "need it" or not, then on their own-branded ones, at least, they put the test sheet right in the box). All new and reman alternators will have a bad one here or there; it's the frequency with which the bad one sneaks through that sets them apart, but for a low-enough price, the retailer will often accept that they have to take a few more back under warranty. (On my car, I remember (and just confirmed in the service records) that the dealer replaced the alternator about a year after delivery. And that was a brand-new Bosch alternator that MB had built into the car.) If you eliminate everything else, I would see if Advance would let you try another alternator unit from their stock to see if that solves the problem; there wouldn't be anything special about the OEM (i.e. Bosch-rebuilt Bosch) one over a properly-working reman one (i.e. X-Company rebuilt Bosch) that should make a difference, but bad units do slip through. Meanwhile, my then-$139 Pep Boys remanufactured Bosch alternator keeps chugging along, 20,000 miles after I installed it.

One thought that is probably remote, but maybe worth mentioning. Did anyone try disconnecting the "new" alternator, checking the wiring harness and cleaning the connectors, and then hooking it back up? That thing is a little tricky to get in and out, just because of the position that a human has to bend down to in order to move it and hold it in place, and the easiest way to remove and reinstall it is to unhook a couple of things nearby to wriggle it out. Something could have been crushed, banged, torn, dirtied, or just not reconnected in the process. Those codes don't point directly to the alternator, but if the concern is that it isn't communicating, checking the connections and the wires to the connections might not be a completely-useless task. Swapping out the pre-fuse with a known good one and checking that, if you haven't done so, might also be sensible.

Or maybe your guy is right and you just need to flash the thing. Sorry that I'm too far away to let you use my hardware...

If you do want to try the new OEM alternator, Amazon is the best place to get it as they sell it for $258.40. At least today they do, as their prices change.

kajtek1

if you are Prime Member on Amazon you have lot of benefits like free shipping, no hassle return etc, but I am not the only one who experienced that don't guys have no idea what they are selling.
They send me wrong set of rotors and fast responded to my complain by sending me another set of identical wrong rotors.

seawind

I took it to the dealer and this is what I got back: "Diagnose charging system fault indicator- pull diagnostic codes, test primary and auxiliary batteries, found batteries to be good. Function test charging system, found alternator output to be within specification. Upon further diagnosis, suspect battery control module to be faulty (insufficient voltage to aux. battery, 12 volts supplied). Recommend replace battery control module, and re-evaluate." The service writer also told me the tech tried updating the battery control module but it was a newer part number and couldn't be updated. I'm assuming he meant it was already updated but I don't know...

It seems the aux battery isn't getting the correct voltage. Because I swapped the battery control module with a known working one I'm assuming this means there must be something wrong with the alternator. Should I still replace the relay with the updated part or should I pull the alternator out, check and clean all the connections first? The pre-fuse was visually checked but I guess I could do a continuity check on it.

wjcandee

Yeah but in this case I searched the Bosch catalog for the right part number, then searched for that part number on Amazon. One thing Amazon is good at is sending the thing that they intend to send, and here they would be intending to send me a specific part number.

kajtek1

What is the mileage on alternator brushes?
They are wearables and seems nobody knows that, while troubleshooting is difficult as for long time they can act intermediately

seawind

Aren't the alternator brushes inside the alternator? The alternator was a reman advance auto parts alternator so I don't really have anyway of knowing but it was replaced maybe 2 months ago now.

kajtek1

Brushes are part of voltage regulator mounted on the back of alternator.
I had bad experience with US rebuild alternator and internet is full of similar stories.
In your shoes I would drive with voltage displayed on the cluster all the time.

seawind

Well guys, I still have the same issue, new things I have done:

1. It's not the regulator brushes! I replaced the voltage regulator on the original Bosch alternator, had it tested at Oreilly's, it tested good so I put the original alternator back in.

2. I took it to Mercedes to have the battery control module (BCM) flashed and they told me it was already up to date and they recommend replacing the BCM.

3. I replaced the BCM with the latest part number A 211 540 86 45.

4. I ran test leads from the red/purple wire that leads in to the polyswitch fuse near the AUX battery to the red/purple wire going in to the BCM. I know the test leads are working cause I'm getting the same voltage that the AUX battery gives on both ends of the test leads. I got that idea from a guy with a similar problem here http://www.benzworld.org/forums/w211...lp-please.html, the only difference is that resolved his issue.

5. Mercedes also tested both batteries and said they were good. I forgot what else they did, the paper is at home but I'll check it when I get off work and note anything I haven't already mentioned.

6. Today I retested all the fuses for continuity, I wanted to make sure I didn't blow any while working on it and they are all good! I tested the fuses on the driver side in the trunk, I tested the fuses on the driver side near the steering wheel, I tested the fuses on on the driver side in the engine compartment, I tested the proximity fuse on the passenger side in the engine compartment, I tested the 3 40 Amp/1 50 Amp fused under the passenger foot-well, and I tested the fuses near the battery on the passenger side. There isn't any hidden anywhere else is there?

Any ideas?

clvincent

I don't know if this helps

But did you replace the bmc or did the dealer do it?

I was under the impression that had to be programmed to the car using star...

seawind

I wish that was the case, according to this it doesn't look like it needs to be: https://mbworld.org/forums/w211-amg/576997-battery-control-module-has-programmed-vin.html

Plutoe

You are under the correct impression---the problem was that one poster led everyone on a may pole exercise looking at brushes---wada shame!!

kajtek1

Looks like you spend quite some money and still have the problem.
Now we can ask Plutoe why DAS did not solve it I guess
Anyway, I like to "hold my hand on pulse" and see what is going behind the cluster in my cars.
In your case I would drive with car voltage display on the cluster all the time and install additional voltmeter to aux battery.
That will not pinpoint what is wrong, but at least will can rule some things out.

seawind

It looks like people disagree, does the BCM need to be programmed or not?

I haven't spent that much, still about $600 less then what the dealer was going to charge me just to replace the BCM. I will drive with the voltage on the dash next couple of days to see if it fluctuates.

Plutoe

That is a question you should be asking the OP----this is once again another Benz W,may pole post---loads of misinformation and confusion about brushes---wada shame!!

kajtek1

That alone will rule alternator issue, but will say nothing about BCM
Now when the message comes?
I know the alternator failure comes after few seconds, about 5.
Would assume BCM not charging aux battery will come later, but MB programmers never had the same logic I do.
I know that alternators and batteries are hard to troubleshoot.
First they can act intermittently and I had rebuild alternator in my Ford having charge light occasionally, when it passed bench test.
Than batteries run on complicated process of converting chemical energy into electricity. Not too many folks understand the outcome.

seawind

The red battery visit workshop message comes on as soon as I start the car, no delay.

I think the Mercedes diagnostic said something about the Aux battery only receiving 12 volts but I'm not at home looking at it so don't quote me on that.

kajtek1

Instant message would point toward control unit fault.
As I said -with bad charging system computer takes few seconds for voltage to stabilize before it judges it low or high.

clvincent

my mechanic was busy the day i got the red battery light so i went straight to the dealer that morning

they tried to update the bcm but it would not take the update so said it needed a replacement

had everything done at the dealer which i dont like to do
but i ask my regular indie some questions later and he commented he was pretty sure we would have needed the dealer anyway on this repair because he thought the bcm needed the star to program it

not 100% sure this is right but maybe you should ask the dealer

seawind

I've been watching the UB voltage and it stays at 14-14.2 while driving. At this point I guess I'm going to ask the dealer if the new bcm needs to be programmed. Thanks for the help guys, will post back as soon as I know something.

kajtek1

14-14.2v is overcharging, especially when you add 0.5V the cluster readouts differs from alternator output.
That would lead to faulty VR. I would take multimeter and read the voltage at alternator, or at least on battery clamps.

seawind

It's 14.25 at the battery when running. I'm in slacks atm so I'll check the alternator as soon as I get home and change. I just changed the VR, would I really have that bad of luck to receive a bad reman alternator/VR and then a bad VR that I used on the original alternator...

kajtek1

14.2V on the battery is acceptable short time after the start when battery needs quick recharge, but should stabilize closer or below 14V after few minutes.

mersum1es

This sounds tricky thing... it is not overcharging, WIS states that charging can go up to 15V. But yes normal rate is near 14V.

Even posting WIS documents is not very highly respected here, few sheet are still worth to read, for example (google them or PM me)
AR54.10-P-1135A
GF54.10-P-1001T
GF15.40-P-0001B


If charging voltage is changed at all, it could in in emergency mode (see one of the WIS doc), then VR gives constant 14,3V output. This could point to faulty VR or wrong TYPE of VR... this is happened many times! On the other hand then star should give communication error fault.

Good luck!

cmriv

I feel like a Multimeter would be able to tell you exactly what is going on. Look at a wiring diagram and or function diagram of the circuit. If you have 14 volts or so at battery with engine running your charging voltage is fine. If this is a 03 I doubt bcm needs to be programmed with star, could be wrong though. Where is the bcm located on your vehicle? Near W/W cowling or in the trunk?

seawind

kajtek1: The UB on the dash stays at 14.2 even after a 15min+ drive. Do you want me to check the alternator output after a drive or after just starting?

mersum1es: I can't seem to find emergency mode mentioned in any of the listed WIS documents, do you know which one you saw it in? I bought a new Bosch VR 0031546506, which according to my research should be the correct VR for my Bosch alternator.

cmriv: It is a 2005 E500 and the BCM is located in the trunk near the battery.

Thanks for the help guys it really is appreciated.