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So to me, this was misdiagnosed, but the fix came by pure chance.
Dudeman - Thanks for offering your opinion on what you think happened, but you don't know what happened here. Your speculation of misdiagnosis and being "lucky" is just wrong. The original owner replaced a SAM and the blower as part of the repair previously. Following the SAM and blower replacements, the dealer cleared all of the faults and the car apparently was okay for some time. Water was introduced into the car floor boards prior to the SAM and blower replacements. To say that this was misdiagnosed and that the fix came by pure chance is really showing how hypercritical this R230 subforum really is. Glad you got your system sorted out, but to make the statement you made above is really out of line. The next step the dealer wanted to do was replace the A/C control panel. The owner declined this repair. Working with Pmercury, he helped me sort out a number of connections - one of which was really corroded due to the water problem. Was that the particular problem in this case? I'm not sure, but Pmercury saved me from buying flap door actuators and a number of other items based on the sole diagnosis from Xentry. That was my point. And if my thread helps others to possibly look at other items such as connectors, then I'm happy. But I've got to say that reading posts like yours really makes me not want to participate in this forum.
Last edited by JamesMitchell; Feb 25, 2020 at 09:44 PM.
Gentlemen: Why so much acrimony over a problem so easily diagnosed as this one? If I were running a shop I'd put the novice tech who usually changes water pumps and put him on this one to relieve his boredom.
There is no communication happening on the HVAC communication (AC) bus. None. I think the odds of a failed push button control unit are pretty strong. If the newbie tech pulls the control unit from the dash and measures a voltage that deviates significantly from 7 volts, he'll bring to me a failed control unit and get 60 minutes for lunch that day instead of his usual 30 minutes.
Of course as was just previously mentioned, the bus could be disconnected, and I imagine he'd figure that one out instantly.
Rod - This was not an "easy" fix. And your post is misleading given the issues that happened to the car. The original MB techs asked to replace a SAM and the blower motor (repairs completed within 12 months of each other) since it was going high and then low. They were replaced, faults cleared, then the problem resurfaced. MB dealership makes money off the repairs. Then owner brings car back in for same problem and a MB tech/ or as you said, your water pump tech recommends replacing the A/C control panel. Owner declines expensive repair. That wasn't the problem. The SAM wasn't the problem. And the blower wan't the problem, but the original owner paid dearly for these repairs. To tell folks in this thread that a connection issue within the A/C system likely wasn't the problem is misleading. MB techs at two different dealerships were wrong in their diagnosis and your post doesn't help DIYers to possibly look at connectors as a problem in a troublesome case like this. Both sets of dealership techs were "out to lunch." I hope what I've written above helps some folks out as they meander through posts like yours. And no, it wasn't something that was figured out "instantly." That's my point in sharing this information.
Last edited by JamesMitchell; Feb 25, 2020 at 09:49 PM.
In this post I found a document on CAN which Mercedes uses to train their dealer technicians. On page 14 is a graphic which shows how a grounded wire does not interrupt CAN communication. Note also that on page 55 it shows that the climate controller N22 plugs into the CAN connector located on the driver side of the car and not the passenger side, which is the one that got repaired.
So I think the screen with all those CAN faults was a red herring and there must be another cause for the stepper motor "mechanical" faults. .
I cleaned the connectors of X30/15, X30/16, X30/17 and X30/18. The one connector that was visibly corroded was X30/16. But all of the CAN connectors and other connectors were cleaned during the process since I removed the carpet and it was clear that water had penetrated the floor boards. The point in writing all of this is to help out others and let them know that Xentry may be telling to you replace an expensive part - like a SAM or a blower motor, that the original owner replaced. But the problem may be with an actual connector and not a component. I was actually looking at how much it would cost to buy and replace a flap door actuator because that's what Xentry was initially telling me. Which connector ultimately fixed the system, I'm not sure. I found the X30/16 one visibly corroded. But I cleaned all of them and other connectors during the process. Thanks for the hypercritical post. And people wonder why folks shy away from posting in the R230 forum. I don't blame them.
Last edited by JamesMitchell; Feb 25, 2020 at 09:54 PM.
And your post is misleading given the issues that happened to the car.
Misleading? Sir, that is the word that comes to my mind when I read the beginning of this thread. If the CAN status shows the interior bus is faulted one would conclude this could cause a problem; in this case, motor faults. Yet as explained by two or three people, it is impossible for a single-wire CAN to affect any aspect of your car. When you accept that ineluctable fact, clarity unfolds and an issue which would seem to have a myriad of causes actually becomes really quite simple.
Cleaning those contacts apparently corrected the single-wire operation on the interior CAN and nothing more.
For clarity I'll repeat what I wrote prior: If your pushbutton controller has all of its motors faulted, the cause is no communication on the AC bus. Period. You can put away the Star Diagnosis, the WIS, training documents, slide rule, etc. Lack of communication to every motor can mean only two things: The bus is disconnected or poorly connected to the rear of the controller or the controller has failed, and that is indicated by not having 7 volts DC supplied to the bus.
Last edited by seven_out; Feb 25, 2020 at 11:25 PM.
@JamesMitchell So basically, you just proved my point. All the troubleshooting that was done with the Xentry, was basically useless, as it pointed to the wrong components as being faulty. It was ultimately a bad connection due to corrosion. And you really still don't know which one, but in the process of cleaning all the X30/xx connectors you made it work, and it's great.
But the point is that these nifty tools like the Xentry or DAS don't always give you the (right) answer. Having some experience and the aggregate knowledge of a lot of people on forums such as this might be a better solution.
Dude, you are the man. But I think Star Diagnosis provided the right answer. Taking the information literally, the CAN was in single-wire and cleaning a connector fixed that. The mistake was to not realize that single-wire had nothing to do with the operation of the air conditioning or creating faults. And that important lesson learned is the value I think these recent posts have added to this thread.
There's one more thing I'm wondering. If there is a screen full of motor faults, you pull the control unit, find the connector attached, and you measure 7 volts (DC?) on the bus, couldn't a broken wire cause that?
Misleading? Sir, that is the word that comes to my mind when I read the beginning of this thread. If the CAN status shows the interior bus is faulted one would conclude this could cause a problem; in this case, motor faults. Yet as explained by two or three people, it is impossible for a single-wire CAN to affect any aspect of your car. When you accept that ineluctable fact, clarity unfolds and an issue which would seem to have a myriad of causes actually becomes really quite simple.
Cleaning those contacts apparently corrected the single-wire operation on the interior CAN and nothing more.
For clarity I'll repeat what I wrote prior: If your pushbutton controller has all of its motors faulted, the cause is no communication on the AC bus. Period. You can put away the Star Diagnosis, the WIS, training documents, slide rule, etc. Lack of communication to every motor can mean only two things: The bus is disconnected or poorly connected to the rear of the controller or the controller has failed, and that is indicated by not having 7 volts DC supplied to the bus.
Rod - you proved my point as to why thinking out of the box and not replacing components is always necessary.
For clarity, I am attaching the below electrical schematic showing how the CAN B system connects to N22 ACC pushbutton control module. Please note the location of X30/15 CAN B voltage distributor connector in the driver's side floor board. As I noted above, I cleaned the connectors to X30/15, X30/16, X30/17 and X30/18. I noted the X30 connector in the pass. compartment seemed to be the likely culprit based on the corrosion, but that I had cleaned all of the noted connectors. Now it's appears the culprit was X30/15 connector. You mention that the only problem would be the connector to the ACC or the ACC unit itself, but it's clear based on the diagram and pictures that X30/15 - which is located in the floorboard also supplies input to the N22 ACC unit.
So if you were advising me, you would likely tell me to replace the ACC unit if the connector behind the ACC was good. But the reality is that the X30/15 unit being corroded could also cause the problem of electrical input to the ACC unit. And in my case, this is what turned out to be the problem and ultimately fixed my A/C problem. Please refrain from making definitive statements based on what you "believe" could be the only two problems with the ACC unit. I hope the below diagrams add clarity for folks reading this thread. Cheers.
Last edited by JamesMitchell; Feb 26, 2020 at 12:39 AM.
@JamesMitchell So basically, you just proved my point. All the troubleshooting that was done with the Xentry, was basically useless, as it pointed to the wrong components as being faulty. It was ultimately a bad connection due to corrosion. And you really still don't know which one, but in the process of cleaning all the X30/xx connectors you made it work, and it's great.
But the point is that these nifty tools like the Xentry or DAS don't always give you the (right) answer. Having some experience and the aggregate knowledge of a lot of people on forums such as this might be a better solution.
Dudeman - Xentry pointed to the correct problem as I posted above. I didn't know all of the electrical schematics or how the various systems worked together as I do now. The reason for my post in the first place was to show forum members that even with Xentry, some folks (like me) may need some help. And in my case I was able to get help with Pmercury to decipher what Xentry was telling me. That's why I called it expert diagnostics. And for that, I had many folks pile on and tell me I was wrong. Well, the above diagrams prove what Pmercury determined was correct. Rod, above, makes this matter seem "simple," and if he were an MB tech advisor, may have told me to replace the ACC unit if the connection behind the unit was good - Just like MB of Plano, TX told the original owner to do. But that was an unnecessary expense and turned out to NOT be the problem. The problem was fixed by cleaning the CAN connectors.
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how do you update the modules please . I have the xentry too sl55 2003
Austin - I'm not sure how to update the modules at this point. I'm still in learning mode when it comes to Xentry/DAS. But when I worked with Pmercury, he updated all of the various modules for me: ECU (which was a 14 minute upgrade itself), the instrument control module, ESM and a few others. The ECU update made my SL65 idle and run much more smoothly. Prior to that, I was considering replacing the spark plugs. For clarity - I didn't upgrade the tune or add any more HP to the engine, I just updated the ECU and it made my car run much better.
You mention that the only problem would be the connector to the ACC or the ACC unit itself, but it's clear based on the diagram and pictures that X30/15 - which is located in the floorboard also supplies input to the N22 ACC unit.
Your diagram is correct. Your analysis of the diagram is also correct. But then you apply your analyses to the general case instead of your specific case and arrive at false conclusions by neglecting two key points.
You had faults stored in N22 which sharply limit the array of possible causes for your issue. Every stepper motor actuator was faulted. Like your expert, I ask myself "why"? What could potentially cause this? Suppose I discovered the fuse to the alarm siren was blown. I think you'd agree with me it surely would not be the cause, and if I were to replace the blown fuse and the motor faults were no longer CURRENT, then this would be purely coincidental. But what about the state of the CAN? To a lay person the answer to that question may be less clear.
Recent posts to this thread commonly mention the "AC Bus". I have a notion that this concept is not well understood, so I have attached a partial schematic of N22 for reference. To the left I have highlighted the CAN connection in a yellow box, and in this case a minor difference between a very early car and other years is depicted. To the right I have highlighted the "AC bus". Do note that electrically the two are completely independent. They share no conductors in common; they share no electrical connector in common. So it should now be immediately obvious to all that the electrical condition of the CAN has no bearing on the electrical condition of the AC bus and the operation of the stepper motors.
That first point renders the next point moot, but I'll explain it nonetheless. As I believe you noted, N22 communication to the CAN via X30/15 is absolutely critical to the function of the A/C. If you were to disconnect N22 at that connector the driver-side SAM would never receive a data message to increase the output of the variable-displacement A/C compressor above its idling duty cycle of 3%, and the system would have no capacity to cool air flow to the interior.
But what if major corrosion caused an interruption in Low-CAN communication as you reported? The consequence would be single-wire operation with no interruption to communication between the control panel and the SAM. So in your specific case of single-wire operation the quality of the connection at X30/15 and the other CAN connectors was immaterial to any operating issues with your vehicle.
Now then, with each and every stepper motor showing a "mechanical" fault, as a practical matter this is a guarantee that no communication is occurring on the AC Bus. Looking at the attached schematic it is apparent that there are only two plausible causes: the bus is disconnected, or N22 is defective. So, for anyone with nothing more than facile understanding of the AC bus (as my novice tech would have) diagnosing the case of every stepper motor faulted is elementary, and the key is that no motor on the bus is not faulted.
Know too that had you double-clicked on any one of those motor faults Star Diagnosis would have provided you with a list of tests for possible causes of the fault, and that scope does not include the CAN. In fact, the list is limited to testing only the motor and the AC Bus. I completely discount a motor itself being a cause since the likelihood of all twelve motors failing within a narrow time window is negligible.
Originally Posted by Seven Out
If there is a screen full of motor faults, you pull the control unit, find the connector attached, and you measure 7 volts (DC?) on the bus, couldn't a broken wire cause that?
No, and the answer may not be as obvious as it would seem to be. But since I am sure I have exceeded my daily limit of typing 500 words, a reply will have to wait for a later time.
Last year, after I replaced my Comand head unit with a Kenwood my climate controls no longer worked, other than the fan, which was blowing basically room temperature air. I put the iCarsoft MBII on it, and I got pretty much the same kind of results as the ones posted in the first image. Every controller and actuator was faulty. It worked before I took the dash apart, but it was a massive failure now. So at Rodney's suggestion, I took everything apart, and it turns out that I had forgotten to put the can wire back into the back of the climate control box. That's all there was. In fact I posted about this in the Comand replacement thread I had on the other Benz world forum:
What I think is happening here is that a lot of testing was done, showing errors and such, but the real culprit was a disconnected wire, which was fixed in the process of dismantling and reassembling everything, but it had nothing to do with the issue on the second photo, because as SevenOut pointed out, that CAN is still functional, even though it's doing so in single-wire mode, which is the fail-safe operation mode. So the non-functionmal actuators and motors could not have come from this CAN.
So to me, this was misdiagnosed, but the fix came by pure chance.
I had the same problem even changed the heater valve on the firewall. Ended up being that wire was unplugged after radio upgrade
Yeah... I guess I’m a mini- hater as well. Seems the Xentry guru puts out misinformation
seriously not
No need to write any comments like this, I will not reply, nobody cares about these pub-discussions.
Nothing to do with this thread, because first of all I didn't write it, James did it and he is one of the greatest grateful and loyal guys around.
but those concerned pointing some words to me know....
I am here to help and as all new joining friends write reviews on me, only more and more join.
So those 2-3 concerned, just help people or remain quite like you have been doing for years or open your own pub-discussion board
Last edited by pmercury; Mar 14, 2020 at 06:42 AM.
No need to write any comments like this, I will not reply, nobody cares about these pub-discussions.
Nothing to do with this thread, because first of all I didn't write it, James did it and he is one of the greatest grateful and loyal guys around.
but those concerned pointing some words to me know....
I am here to help and as all new joining friends write reviews on me, only more and more join.
So those 2-3 concerned, just help people or remain quite like you have been doing for years or open your own pub-discussion board
Now you're just ranting. You're the one who had to take a jab at those that disagree with you by calling them "mini-haters". And now that you get some of it back, you hide behind your buddy James.
Frankly, by now, I think a lot of people on this board know who you are and what you're about, so all this talk about grateful and loyal fans is just that, talk.
If you are reading this please be aware there are at least 3 members in this thread using multiple accounts to promote their view or bias. Those accounts will be reviewed and removed, have nice week end.
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