SO there are just a few posts showing this particular code. I went through the flush and cleaning of the solenoids, found some dark matter, used a magnet. Put it all back and bam limp mode and the P0748 code is persistent. Took it apart, tested the solenoids for clicking at 12v just the blue click the black make a different noise more like a buzzing.
Resistance is 5.6 plus or minus 0.2 so good. Did not check to see if K1 holds pressure through, not sure how to do that, probably need a hose and a hand pump and 12v. Anyhow, so been reading a lot the next thing is the plate. This conductor plate seems to be the culprit in a lot of issues with speed sensors and stuff, but have not read anything about it causing P0748 code. So if you guys know anything of the sort please inform. So the options on this is replace the K1 with 130 at the dealer and see o benefits as per some suggestions or replace the conductor plate. I found a place that repairs the old one for 399 no need for reprogramming whatever that means. I also found a place locally in Santa Monica CA that gives you a new plate for around 800 bucks and charges you 250 to marry it to the car and more software adaptation stuff. I do have access to a Star clone system but my friend say you have to be linked to somebody online that will do the programming for you. Don't know.
Tranny conductor plate is VGS3 from 2010.
What can I do and has anybody fixed this issue with this code and limp mode. Thanks in advance.

 

Usually the issue with the conductor plate is the speed sensors... if you have access to Star (Xentry), then pull codes with it and clear them. Some generic scanners cannot clear TCM codes. I'd do that first... before going down the rabbit hole. Also with Xentry, you'll have options to run guided tests, along with diag info.

Outfits that fix your original conductor plate won't require coding or adaptation. If you get a new one from dealer or outfit selling virginized (used), then you'll need someone with Xentry online to unlock and code the plate. Then with Xentry offline you perform adaptations.

 

I do have access to the laptop star(xentry) deal. Any idea which way I should direct the search. Just look for codes from the transmission option? We actually used it and it was the only code it found.0748 k1 solenoid. Can the old oil that is still lingering in the valve body cause this to happen?
These are some screenshots of what it saw from the TCM

 

Assuming you've tried clearing and it comes right back.

Click Tests, under the first picture, after you click the fault within the module. Obviously the solenoid can be bad, there's a chance the conductor plate is/was bad or damaged in some way. I'd probably throw a solenoid at it before replacing the conductor plate... especially since it not a common fault, nor are there multiple faults present either.

I suspect the solenoid in question is: Y3/8y1 Working pressure control solenoid valve

 

So is there a way to check the solenoid besides what I did, 12v clicking, and resistance. There is also the pressure test 20psi and click 12v to see if it works.
Found these 2 threads

https://mbworld.org/forums/m-class-w163/454567-p0748-stuck-limp-mode.html
https://www.benzworld.org/threads/limp-mode-722-9-connector-and-p0748.3011364/

 

Since you aren't getting codes for the other solenoids... you could temporarily swap the "bad" one with a "like" colored solenoid (blue vs. black) and rescan for codes. If the code doesn't change.. then is likely the conductor plate. If a new code pops up, then is likely the solenoid. Don't forget to put the solenoids back to original location.

 

The 722.9 doesn't suffer from the same connector leaking issue as the 722.6. The .9 variant integrated the TCM into the conductor plate and the connector is molded-in... so there's nothing to leak into the vehicle harness or connector. Totally different design. The only leak would be past the o-rings on the molded connector and transmission body, which would just be a leak... no affect on electrical connection.

 

0748 The internal electrical check of component Y3/8y2 (K1 clutch control solenoid valve (VGS)) has failed. Solenoid filter(s) may need cleaning, or replacement.

 

So you are saying switch the K1with another blue cap and just plug the connector in without adding fluid and just check the codes, clearing the 0748 first. Unplug and see what changed if anything, switch it back and buy plate or solenoid of confirmed.
I just cleaned the are one more time and rechecked resistance it's 5.2 on all.
I will try what you said it makes sense.
I usually did that on other issues.
The only reason I didn't do it is because they said not to move them around since they are adapted in their respective slot.

 

If I don't start the engine I can still plug the valve body to check codes without the fluid in right? Friend pointed out not to run the pump dry. Let me know so I do it right.

 

I am using the Autel 708 it has the same tests as the Star I compared. Went to Control unit group under Drive Transmission I erased the 0748 code and reread and it is back.
Another thing when I go to live data hear change I shift to Drive and the program shows neutral for reverse it's the same thing.





Obviously could not get to the control adaptations




Clear codes turn off 10 seconds read codes and dame code 0748

 

Which pump are you referring to? Seems to be a hard fault, as soon as its cleared it comes back. Your not starting the car in between reading and clearing, right?

My logic would be swapping the solenoids and just plugging in the conductor plate into the vehicle wiring should confirm if the issue follows the solenoid. I can't speak to the Autel... it looks legit, but I would use Xentry to rule out any scanner driven issues at this point.

If the range selector valve is not hooked up properly, you should get an error code (essentially the direct shift expects gear X and sees Y). Why is the Autel displaying neutral, when D or R are selected...?

 

Was talking about the tranny pump, if it is safe to rest dry. I did not start the car between read and erase and read again.
I did turn key off 10 seconds.
I will use the Xentry tomorrow. The only difference so far has been the fact the xentry gives explanations about the faults. The Autel has been spot on. Even my friend said that it even boots faster.
I did have some odd codes this time around 2 extra on the tranny.

The blank top one is the 0748.

This was in Parktronics.
I think I engaged valve body wrong at the selector it only let me go to D and wouldn't switch back. They must be related.
So do I need to fill with fluid and start the car to properly do this or is the valve body connection sufficient?
1709 and 2805 are related to the selector not showing the right gears. Like I said it was dark and I think the selector on the plate did not go in properly.
Everybody I ask say the plate only fixes certain codes. It's the TCM that does the 0748. I wish I could copy virginize and reprogram it to see if maybe the software is off on it.
M y friend mentioned you have to get an online internet deal to do it. Or it can be done by buying it on EBay and somebody can use the xentry he has online to program.
Like I said I am helping out a friend with this not making any money on it.
Really appreciate the help here.

 

Does the car have ECO start/stop... if not the only transmission pump is mechanical, e.g. engine needs to be running for it to be operational. Now if it does have ECO, then there's a electrical pump that runs. That, I'm not sure of, whether it'll run with the engine off vs. ECO off. I suspect, it would only work during an ECO stop.

Yes, the conductor plate usually suffers from a certain fault. However, electrical connections exist between the TCM>conductor plate>solenoid... so there's a possibility the conductor plate could be bad. I think the likelihood is the solenoid itself is bad or dirty like konigstiger posted. I'd be inclined to swap test and/or replace the solenoid first, before throwing other parts at it.

 

I already swapped tested with 2 different blue cap solenoids. I documented it all above. Same thing. The car doesn't have eco. I know it has a mechanical pump they all do. I also listed and showed pictures of all the codes I found in the auto scan. Look above.
I did not start the car just turned the key on and off for read erase and read again.
0748 comes right back.

 

Guy that started this thread had the same issue. Post #29 describes his successful repair:

https://www.benzworld.org/threads/code-p0748.1416106/

 

You need a conductor plate....... Period. I highly recommend you go with a new one, unless you can find a used one version 3 made by continental. All Siemens version 1, 2 and 3 have many failures.

 

OK so a new continental conductor plate complete with the control unit that's in the center right? Should fix the P0748 issue.
I am going to provide some images of what the Xentry saw today when I used it for testing.

This says possible cause control unit defective.





So the Continental plates are the best? I have to check for one or is the dealer the only place to get one?

 

I highly recommend a brand new one....... But you will not be able to purchase this part. Only shops with licensing through NASTF can purchase this part from dealer, here in the US. And even if you were able to purchase, then you would need access to the online system for programming and SCN coding. Is possible to do offline with Vediamo and DTS Monaco, also. You just need to find the correct CBF and Coding. Where are you located???

 

I am in Los Angeles CA. I can get one time access to accounts online from China.
There is no way to cope the old to the new offline? There is a guy on Youtube doing that. Don't know if it's legit.
So with my own Star Xentry set up, what do I need to do to get the used good Continental valve body and conductor plate
Plus TCU working on the car.like I said I am helping someone. I have been on this issue for a week now, for free. I have a few armenian friends that are looking into a source to program, but since I have the Xentry and can get a one time account for40 bucks, how hard can it be? I might need more than one access.
This is taking way too long. Poor guy is overwhelmed by all this.
Anyways thanks for contributing here, will wait for your input.

 

Your first road-block is obtaining the new conductor plate.

As far as coding a new or virginized used unit, the "fool-proof" way is online... offline in Vediamo/Monaco, one slip and you can brick the unit. Personally, I'd pay the fee to gain access to MB server via the surrogate. If I recall, part of the process also entails transferring flow/electrical parameters of the solenoids/valvebody.

 

Of I find a used unit with the valve body do you know how to verginise it with the Xentry?
https://www.ebay.com/itm/293839323064
https://youtu.be/1MPW5NpF8bY

 

Read a bit online and it seems Albrites is the soft used for virginising. I don't know what hardware you need I downloaded the soft. There are youtube videos on virginising.

 

Yes Abrites can virginize and change the VIN, but comes at a high price. I highly doubt the Chinese will be able to log in to the online system with your set up. Mercedes is blocking unauthorized laptops/PC's. Pretty much whether you are installing a new or virginized one, the steps are the same. Valve body flow data needs to be read and transferred. After, you need to perform programming, SCN coding, personalization, activation and range sensor calibration.

 

my indy here in santa cruz has the whole xentry system. the owner is probably the only guy in the shop who can use all of it, but he runs a tight ship, and they can get you in and out in an hour on an A service if you time it right.