W211 CAN Bus problems - Page 2 - PeachParts Mercedes-Benz Forum

jay_bob · #16 10-08-2019, 08:17 PM

Quote:

Originally Posted by TimFreeh

Seems like a reasonable diagnosis to me, why is the alternator a networked device? Are they doing some sort of trickery to bias the alternator charging scheme to periods of deceleration or something? What is the text associated with the 2263 error?

The LIN bus is a one wire low speed serial link used for comms that are not as critical or sensitive as those requiring full two wire CAN. The 642 uses this for the glow plug relay (starts and stops the glow cycle, reports bad glow plugs back to the ECU) and for the alternator it provides tighter regulation than the traditional feedback wire method. There is a current sensor at the battery so the ECU can make charging decisions based on current demand on the system. Such as telling the alternator to stop charging while at idle and low demand to reduce drag on the engine, or killing it at full acceleration to reduce the load on the engine. By dumping the field excitation to zero, the alternator basically produces no electricity and just free spins. Combined with the freewheeling clutch the alternator drag can be reduced to nearly nothing on demand. All to chase that almighty drop of fuel savings....

It appears the default behavior in the event of LIN bus loss is to maintain 14.2-14.4 V on the bus whether it needs it or not. It does inhibit the booster heater in this condition.

The error text was in my post above in italics.

jay_bob · #17 10-08-2019, 08:24 PM

Quote:

Originally Posted by KrustyKustom

I am dealing with a front passenger side SAM unit defective right now and some of these modules are starting to be become rare, the one I need is not in the USA and none in stock in Germany. Supposed to be 4 weeks. The bummer on these newer gen tech cars is if your SAM units/ECM units go there is no subsitute for not getting new modules. You can find used ones, but dealers will not program used parts and unless you have a really old version of the Xentry there is no offline coding available.

I was able to get the alternator for around the mid $400s with exchange, or double what NAPA charged. This is a remanufactured unit certified by MB. I need to turn in a core at MB so I am going to just give them the NAPA unit since it will be almost $200 more without the core.

I will be pulling the alt tomorrow evening when I get back from my trip and swapping it Thursday morning at the dealer. Also ordered up new brakes, rear pads and rotors, front pads, so I have another weekend project ahead for this car.

I am too concerned about electronic module failure killing this car. I am glad I was able to save the ZGW module on this car, I guarantee it’s not cheap at the dealer.

KrustyKustom · #18 10-08-2019, 10:44 PM

I have been awaiting the arrival of the front SAM unit for several weeks and it is still showing not available in inventory in the US or Europe. They do not give you a eta when it is awaiting to be made apparently.

So, I have bought a used one. (hope it is good). Taking it to a independant shop with subscription service Xentry to get it coded. I downloaded the code from my SAM onto a thumb drive through my Chinese Xentry, but I cannot upload to the SAM with the C4 version as it looks for a server login.

Working with the CAN-BUS is cumbersome as the vehicle gets older in my opinon but I sure like the W211s!

jay_bob · #19 10-09-2019, 07:49 AM

Quote:

Originally Posted by KrustyKustom

So, I have bought a used one. (hope it is good). Taking it to a independant shop with subscription service Xentry to get it coded. I downloaded the code from my SAM onto a thumb drive through my Chinese Xentry, but I cannot upload to the SAM with the C4 version as it looks for a server login.

Yep that is the problem with the cloned diagnostic units. It’s worse on a 212 and 166, not only can you not upload to the modules, you can’t do the download nor change options (version coding) without logging in. All you can do is scan for faults, run the guided tests, and you can write to the maintenance log (when completing services). Granted that is better than nothing but going forward they really have it locked down.

It’s like the gps maps, on the 211 you can just pop a dvd in there and as long as the data is valid (Meaning a good copy) it will accept it. On the newer models the map comes on an SD card that is hard coded to the VIN. Meaning that you have no choice but the dealer.

On my 211 I bought an EBay copy of the last update that will ever be made (2014) for about $20. MB still selling for $350. I normally don’t advocate piracy (I write code for a living so yeah it’s personal) but come on guys, I am not paying $350 for a 5 year old map that has no support path going forward. I just got tired of it telling me I was off the road every time I drove on a section of roadway near my house that was reconfigured in 2005.

So that same thing will happen to the later models.

I think you are going to see people start offering board level repair of these modules as a service. There are people out there with access to specialized tools and knowledge to be able to troubleshoot these boards.

jay_bob · #20 10-09-2019, 08:29 PM

Quote:

Originally Posted by jay_bob

There are 4 modules on a W211 that connect the engine and body CAN buses together. The ZGW is the primary connection and the only one that can pass packets between the two networks. There are 3 other modules have double connection to the CAN buses, so they can read and write each bus, but cannot bridge data between them. I reverse engineered the wiring diagrams and made a one page tree diagram of the networking in a W211 and then found the actual diagram in the Star Finder utility.

I found my notes, here are the 4 modules that participate in both buses:
N93 Central Gateway
N80 Steering Column Controller
A1 Instrument Cluster
N73 Ignition Switch

jay_bob · #21 10-11-2019, 08:05 AM

New alternator came in yesterday at the dealer. Valeo factory re-manufactured at the Valeo factory in France. MB logo on the part number label. Looked like a new alternator.

Got it installed last night and car now scans completely error free on the quick test.

I started it with the voltage on the display and it appears the LIN bus connection holds off the alternator from starting its charge until the engine gets up to speed and stabilized (or about 10-15 seconds) after start. So much so that I thought it was not working at first.

Without the LIN connection the alternator just starts making 14.xx V right away. With the connection, the alternator slowly walks up to full output once the engine is stable. So the alternator definitely defaults failsafe on comm loss which is a good thing. It just doesn't have the optimized operation without the comm link.

Some tips for alternator replacement on a 642 powered W211 sedan. I suspect the steps will be similar for the W164 and probably the W221.
- I recommend you go ahead and procure the gaskets and seals on all the joints on the intake tract. If you just put it back together with the original seals you will end up blowing black crap all over the front of the engine.
- You will need E10 and E12 sockets, 7 mm (for Y-pipe) 13 mm (for the B+ terminal) and a T20 bit.
- All references to left and right follow vehicle convention, left = driver, right = passenger (for a LHD vehicle).

- first be sure to disconnect the battery. Put a big note to self not to shut the trunk while the battery is off as the trunk is electrically released.
- jack up and remove front and center bottom covers. You can do the whole thing from the top at least for removal but for replacement you will probably have to work it from below. You do need to be able to unplug the intercooler air hoses from the intercooler to get them out of the way, thus the need for lower access all the way up front.
- Next will be a plastic cover over the belt drive. There are two E10s on top and the bottom is held by a ball and socket plastic tip at the bottom of the cover. Pull hard straight up.
- Take off the triangular resonance pod above the mixing chamber (right side). 3 x E10.
- Take off the left and right intercooler hoses from both ends and remove them to get out of your way. The spring clamps are a little tricky, you just find one end and slide back about an inch or so until it clicks in the released position. This allows you to remove or insert the hose. Then when you've reinserted the hose you just snap the spring clamp back to the locked position. Be ready you are going to get a drop or three of oil out of these.
- Take off the discharge side muffler (down front on left) and the silver tube coming from the turbo outlet. 2 x E10 on the muffler, T20 on the clamp between the muffler and the silver tube, deep E10 on the stud holding the silver tube. Pull the muffler and silver tube out of the car. Mind the o-ring at the turbo outlet, that is probably hanging inside the female end of the silver tube, it needs to be on the neck of the turbo when you reassemble.
- Take off the Y-pipe, the right side air box, and the right side air box intake tube. The left side air box can stay.
- Unplug the glow plug relay B+, glow plug relay connector, pressure sensor (up front on mixing chamber), servo valve (on top of mixing chamber), temperature sensor (behind mixing chamber).
- Remove the two E10s holding the right end of the mixing chamber to the bracket supported by the engine. This is right by where the intercooler return hose plugs in.
- Remove 4 E10s at the top end of the mixing chamber, where it attaches to the intake manifolds. This is right at the center of the V. There are 2 bolts right next to each other at the top of the connection. One holds the fuel hose bracket and the other actually attaches to the manifold. Don't mix up these bolts as they are all different lengths.
- Remove the last E10 holding the mixing chamber, that is on the bracket that also holds the glow plug relay, going into the manifold next to the vacuum pump.
- Grasp the mixing chamber and gently pull forward. It will take some persuasion if it hasn't ever been removed. Gently wiggle and pull and it will come off. More oil drops.
- Remove the bracket that holds up the belt cover (2 x E10).
- Put a 17 mm or a big E-torx (my set didn't go that high so I used a 17 mm) on the end of your breaker bar. On the belt tensioner there is a cast E-torx fitting that is at the bottom of the tensioner assembly. Put your bar there and rotate counter clockwise to release the tensioner. Don't use the bolt at the center, that is the bolt that holds the tensioner to the engine. Pull the serpentine belt off.
- Remove the little bracket that held the tail end of the mixing chamber to the head. 3 x E10, 2 of them are shared with the heat shield over the exhaust manifold. When you go to put this all back together, start these screws but do not tighten them until you have attached the bracket to the mixing chamber.
- Cut the two zip ties holding the wire pack to the bracket above the alternator.
- Using a 13 mm (double check you did lift the battery negative first) remove the B+ connection from the alternator. The terminal cover is probably going to be brittle so be prepared and get another when you order the alternator.
- Unplug the LIN bus connector from the back of the alternator.
- Loosen the 4 E12s holding the alternator to the block. Guide the alternator out the top past the radiator hoses. The bottom rear bolt will not be able to be removed with the alternator in place because it hits the sway bar. Likewise the top rear bolt hits the wheel well. So you will be lifting it out with the bolts still in the pockets.

Putting it back together:
- Alternator back in, remember to pre-load the two rearmost bolts and the bracket before setting the alternator in place. Also load two new zip ties in the bracket while it is out, much easier to do now than once it is in place. 20 Nm on the 4 big bolts.
- Hook up alternator B+, 15 Nm, don't forget to plug LIN bus connector back in. Dress the wire pack and secure the zip ties on the bracket.
- Put the belt back on
- Cover bracket, 12 Nm
- Mixing chamber bracket, these are all 9 Nm, leave loose.
- Mixing chamber, all 9 Nm, watch the harness routing to the glow plug relay. Go ahead and plug everything back in on the mixing chamber. Go back and torque the 3 bracket bolts, 9 Nm on these too.
- Turbo outlet tube and muffler, bolts to block are 12 Nm, the T20 clamp screw is 6 Nm, the stud holding the tube to the manifold is 9 Nm.
- Intercooler hoses, be sure they are inserted all the way, the spring clamp is locked, and they pass the 'tug test'.
- The little triangle resonance pod on the mixing chamber, 9 Nm.
- Belt cover, 9 Nm.
- Y-pipe and right side air box.
- Bottom covers.
- Reconnect the battery. Reprogram the limits on the windows and the sunroof. The clock should set itself once it finds the GPS signal (assuming you have navigation option as most 211s did).

When you go to start it, get in and shut the door. Turn key to 1st position and set the LCD so it is showing '0 mph'. Press and release the instrument lamp dimmer knob 3 times quickly. It should show 'Ub = 12.x V'. Start the engine and verify that the voltage climbs into the 14s within about 10-15 seconds.

If you have Xentry then hook it up and go into Control Units/Drive/CDI 5 - Common Rail Diesel Injection/Guided Tests/Alternator Test and follow the prompts.

TimFreeh · #22 10-12-2019, 11:15 AM

Wow. Very comprehensive and detailed list - I'm sure it will come in handy for someone in the future.

I've changed the alternator in a W211 OM648 version and I sure don't recall it being anywhere near as involved as your list. I guess the OM642 engine bay is way more complicated?

I realize the LIN data bus isn't a very complex or expensive set-up and was custom made for this sort of application but I'm just not sure the added complexity of having a computer networked module living inside the alternator is a cost/complexity thats worth the benefit. Electronics isn't my strong suit but it just seems like the standard voltage regulator methodology would be 95% as good?

I guess one side-benefit of having a LIN networked alternator is that you could bias the charging scheme of the alternator to take advantage of deceleration?

I mean how much fuel could that save? An ounce a tank? Maybe?

97 SL320 · #23 10-12-2019, 05:34 PM

If a MB dealer or independent shop was working through this problem, I wonder how many on this list would be screaming that they could not fix the car the first time, that the dealer is just trying to sell them an alternator they don't need and end up trading in the car never finding out that it really needed the other fixes and an alternator?

dieselbenz1 · #24 10-14-2019, 08:59 AM

Nice post lots of good information. I can't help to think that economical vechiles sure cost a lot.

jay_bob · #25 10-14-2019, 09:43 AM

Quote:

Originally Posted by dieselbenz1

Nice post lots of good information. I can't help to think that economical vechiles sure cost a lot.

I’ve had this car since spring of 2018. I bought it for $9k cash from a private seller. It had 179k on it then, now it’s about to turn 200.

Car did not have OE windshield when I bought it. Cracked soon after I got it and replaced for free (SC law requires your insurance to provide zero deductible windshield replacement if you have comprehensive).

Glass man (local independent shop recommended by dealer) commented on crappy job done previously and he spent time doing it right with a MB genuine glass.

So I really think the ZGW corrosion started by hack windshield install letting water in.

Likewise an Indy garage did the oil cooler seals but did not replace the intake tract gaskets. Which blew black crap all over everything on the front of the engine.

So these two faults caused by improper repairs.

Only other thing I have had to do is rebuilding front suspension, that comes with the territory of getting to 200k miles. And about to replace the back pads/rotors (probably original) and front pads for probably the 4 or 5th time in its life.

And a VGS replacement, went dealer on this as I wasn’t brave enough to try the ebay sensor replacement route.

Except for the hiccups with the ZGW and VGS it has been quite reliable.

KrustyKustom · #26 10-14-2019, 05:05 PM

I too have pondered many times the logic behind buying an older used car (mainly a Benz in my case) and economics. I have bought several W211s and a w124 with alot of miles on each, very different experiences on all of them. However at the end of the day it is so much cheaper to drive/repair an older car i feel since i am doing 90% my own repairs than take it on the chin i with a new car (say 60k) and depreciation/upkeep as well.

I can drive a older W211 for 150k miles for the price of a year payments on a new car. Granted I have the inconvienence factor as repairs are needed sometimes when you least need them but I do not have cash to burn!