When was the last time a fluid filter change was performed? If unknown, it may be worth doing so and inspecting the current state of the fluid and valve body. How many miles on the trans? If a lot, a Transgo shift kit may be helpful to restore valve body performance.

One easy check before starting to tear into things is to pull the trans harness connector on the side of the trans just above the pan. Inspect that for trans fluid wetness. If the connection is wet, it can create a host of electrical issues. There is a replacement coupler with new o ring that can cure that.

Good luck

 

@Benzrokee , 70k milles on it, regular max 10k oil flushed. heard about the plate/connector fails, i am considering changing them no matter just as prevention buti m not getting any indication of a connection /connector malfunction
Transgo Sonnax options does need to drill the VB, it needs an coordinate machine, right?

 

The conductor plates occasionally fail, but I would be surprised at your mileage, maybe a transmission shop can dig deeper into the TCM to see if there are more codes. The connector seal though, that should be replaced if original, a known problem.

The Sonax kit requires drilling, the Transgo does not and has all drop in parts. I like the Transgo kit for the innovative approach and ease of install. Again, though, with only 70k miles, unless it was severely abused, lots of towing, I would be surprised if you have valve wear. Sounds electrical, or TCM related.

 

I just had it diagnosed, we drive and monitor it for 30 min.
Despite we drive it slow, moderate or agresivelly, manual or auto gear shifts, the temp was low and no code popped out.The TC was not slipping at all, looking like a new part and here s their explanation for the yesterday event - A 4 th gear slip have occured and placed the trans in limp mode, that s why it was stuck in 2nd and 3rd hence the reason the oil temp had gone that high.
Pretty logical but this doesen t explain why the trans was lacking power/pressure.
@Benzrokee , you sayd it could be electrical/electronical but again, i can t see how it can be electrical when i m having a lack of pressure but no related codes.
Now i m even more siderated about this anoyng issue , they sayd the TC look ok and that the 4th gear k3 clutches could be worned out.But again, even if the 4th gear clutches are worn out, this also doesen t explain the loss of pressure i m having. On the other hand they say that the loss of pressure could be related to the TC, that s really awkward and contradictory and i m not ready to throw that much money to fully rebuilt the transmission, the VB and the TC as they aren t cost few hundreds, actually few thousands

 

When they have thrown a code up and gone limp mode they are sluggish and unresponsive or lacking power as you quoted.
These 722.6 gearboxes do all kind of weird things when the conductor plate goes bad or the electrical connection which is often called the pilot bush is contaminated with gearbox oil.
Look up on Mercedes forums where you will find more info

 

Okay. Just so that I'm clear.
Currently, the transmission is functioning normally and the transmission shop has found no codes or explanation of the cause?

If so, the approved Mopar procedure is: cross fingers, and hope it doesn't come back 😁

If it does come back, will need diagnostics. The 722.6 has quite a bit of electronic control. There are at least 6 solenoids on the conductor plate. They control modulating pressure, shift pressure, TC lockup and all of the gear shifts. An electrical issue with either the TCM, harness, VB connector, conductor plate, or individual solenoid can cause this issue, possibly in either the TC lockup or pressure modulating solenoids or plate. Monitoring live data, TC lockup percentage etc would be helpful.

IMO, in order to enjoy these vehicles affordably, it is necessary to augment either the diagnostics, the repair, or both. Understanding that everyone's circumstances differ, the one accessible to all is the diagnostics side. For $50usd or less a good scanner can be had. There are 2 most often mentioned. I can only recall j-scan but there is another, do a search on the forum. With these, you can view live data, perform diagnostics, adaption and a host of other functions, saving quite a bit vs a shop.

One last thing that you could try is to reset the shift adaptive memory. This resets, the shift pattern memory and starts to learn your style of driving all over again. Initially the shifts will be snappier, but will adapt. Typically you would do this thru a scan tool, but there is an old school carryover from Mercedes that should still function without a scanner at this LINK

 

Yes the old school carryover does work , I have used it before on my GC.
Cheapest option if it does it again is fit a new conductor plate and pilot bush and it will take around four and a half litres of fluid ,it does not empty all the oil out when you only remove the gearbox sump.
Strange gearshifts , hanging onto gears , not changing gear until you lift off throttle , thumping downshifts , esp between 2-1 esp at low speeds… I have had all of these on a Mercedes w210 e300d and had the 2-1 thump and holding gears on my 06 3.0GC.
Always feels like it’s new gearbox time because of the odd behaviour but 95% of the time it’s just conductor plate or a solenoid or oil soaked pilot bush.
The solenoid for 4th gear could be bad but I’m not sure if it would affect another gear change as well ?.
Once you get gearbox codes then as you have found you cannot manually side shift the gears , you can still get limp mode and have no warning lights showing straightaway so flicking lever over to try and side shift will let you know if it has gone into limp.

 

Thank you folks.
I m using witech and j scan @Benzrokee .
Again the only code was the gear ratio error in 4th, i have cleared it yesterday and today nothing had appeared during the testing, the gearbox worked as it does the temp was low, their explanation as mentioned but that doesen t solved the mistery of lacking power.
However, it could be as @Dougdarri sayd that when it goes limped it behave like this and i wont argue on this as i have no experience with those scenarios.
But the point is that i know my Jeep and i know how strong it used to pull when the D or R were selected, no matter hot or cold, now it s half that strong and even weaker when it s hot.
I see no other option than to start gather the parts/upgrades for a full rebuild hopefully i can source them at a reasonable cost. so far i allready got a Mopar repair set (see it has the clutch discs, o rings) and will continue to search for a VB & TC but the upgrades are pricey, more than 1k for a suncoast TC.Upgraded VB see that runs for another 500 to 1k.

 

Try resetting the adaptive shifting and see if it clears or still seems low on power.

The 722.6 is a very strong transmission, IMO mechanical rebuilds are rare unless severely abused, they tend to have a long life. The electronics, much less so. Luckily, all of the major electronics are on the conductor plate above the VB, easy to access and work on with the transmission in car. A few hours of labor and the conductor plate can be renewed, any bad solenoids changed etc. At that point, would be good to do a Transgo VB kit since it is inexpensive and addresses some common PM issues and the VB is out of the trans. Depending on what you want to do, the cost should be less than $1k. You can always go crazy and get AMG solenoids, upgraded VBs and TCM etc. but this will drive the price up considerably. Probably worth it for a real sports car, but for a GC other than an SRT8? Up to each owner to decide what it's worth to them.

Best of luck, hope you find a resolution.

 

I did reset the adaptation, EGS initialized as well when i first noticed the transmission was starting to loose the force but this didn t help and later i got also the mentioned event @Benzrokee
I just want it to be strong and deal the hp/torque numbers as well the heavy drivetrain it has to run on my Jeep. Nothing more, just a reliable drive.
I m aware that those transmissions are strong, i ve even heard the finn s are running them stock on 1000hp projects but i am where i am.
Not that i won t like them but can t justify the need of the AMG blue solenoids and the faster shift they will provide, therefore their cost.
I was thinking about an upgraded TC as this is the first part to handle the force, i understand also that it will help tranfering more power to the ground.
I m thinking also about a VB improvement ( it can be a Trans go kit, see that the SIU tehician adviced them too), and i m thinking also on some better clutch discs .
At the rebuilt time, the conductor plate and the connector will be changed as well.
If i m wrong or if there s something else i might ad to beef it up , please advice, your expertise/experience in this matter are obviously above my level and i thank you in advance

 

The SIU instructional videos are an excellent way of getting a good base of understanding on these transmissions. I am by no mean an expert, I try to keep from rebuilding them, rather than gaining experience by rebuilding them. The videos have an excellent tutorial on the TC, and how it engages and disengages, which was a novel concept at the time. He explains the potential upgrades to the clutch pack etc. Also the hydraulics and their tie back to the solenoids. All very informative.

You can get a lot of info from the Mopar sports folks, the SRT8 people etc, they have extensive info on upgrades that they have used and know what works and what doesn't. Me, I'm just hoping I can get 300k+ trouble free miles out of mine, already more than halfway there

 

I have spoke with some people for the upgrades and first we need to properlly identify the transmission.
They say the NAG 1 had 2 variants, 300nm of torque or 580nm, respectively W5A300 and W5A580 and that most likely that the last one had been used on heavy models.
I understand that JK Wranglers were equipped with W5A580 but according to the buildsheet my WK transmission code is W5J400.
It is 400nm rated? I m getting pretty confused right now.

 

...I'm on this as well... changed the conductor plate, no luck. Opened up the TCM to check for oil contamination, no luck here as well.
My symptoms are similar to OP.
on the very first moment I drive the car, the gearbox seams to do its thing. As soon as I turn arround the block, I can feel the gearbox seting itself up into limp mode. It litteraly feel like a switch is beeing activated. Keeping driving it for a few corners and the gearbox is getting more and more sluggish :/
Starmobile codes:
P2767 TCM
U0402 FDCM
U0415 FDCM

Any advise would be appreciated.

 

The UO415 is a ABS code , sort that out and then see if the gearbox codes still exist

 

Sir,
Roger that but starmobile links it to FDCM.
See picture:

 

It will do as the fdcm needs an ABS input to be able to work out wheel speeds ..any faults or weird readings will affect gear changes and 4WD operation

so in a straight line driving it’s ok but start to turn …

“on the very first moment I drive the car, the gearbox seams to do its thing. As soon as I turn arround the block, I can feel the gearbox seting itself up into limp mode”

 

humm... But if it would be a wheel speed sensor wouldn't the PCM store code related to wheel sensor. On a another note I've used this oil with 236.14 spec.
Would it be possible that wrong oil causes similar symptoms ?

 

It's electrical, either a data or connectivity issue. If you can read live data for your WS sensors you may be able to assess the consistency between all 4 in a straight line. If one of the WS sensors is off data wise, it will be off both straight or while turning.

If no data issue is found, check to see if there is a difference between turning left or right. There is the possibility of physical grounding on the WS sensor harness with the hub knuckle assembly while turning. That's my pick. A momentary short could throw those codes but not a WS sensor code if otherwise working fine. It's easy to inspect and insulate those WS harnesses and ensure they are routed correctly and affixed to the hub carrier.

 

I haven't checked yet for the wheel speed sensor, but here is something strange.
Starmobile can't delete the u0402 & 0415.
When I action the clear code command, its telling that there was a problem when trying to delete the code :/

 

Based on the few codes you have i Highly doubt this has anything to do with wheel speed sensors. The P2767 code refers to one of 2 hall effect speed sensors built into the conductor plate inside the transmission that measure input and output shaft speeds. The 2-U codes are communication codes meaning information was lost on the CAN bus so nothing that can be physically attributed to.

The hall effect sensor sends information to the TCM which then talks to the FDCM, PCM, Steering modules etc so if one gets bad information then they all do. You were able to erase the p2767 code but the implausible data will stay until the condition is resolved. If you drive around again, does the 2767 code reappear? if so then i would suggest you need a new conductor plate complete with the hall effect speed sensors. If it doesn't then you may have a faulty connection somewhere. You can still find the Factory service manual on this forum and it has specific points to test for voltage and resistance to diagnose the connectors and modules.

Good luck

 

Does anyone knows what this connector is all about ? 2008 WK CRD

Pic1
Pic2
Pic3

 

On the wk 3.0 diesel, does the transmission range selector system (aka shifter assembly) requires programming to be replaced ? TCM to Range selection matching is done through can-h and can-L according to 722.6 manuals found online.

 

With the NAG1 transmission, the shifter assembly has a module in it that talks to the TCM ( it is not found on either of the V8 WK models with the 545rfe transmission) . Sometimes the module connectors get corroded and can be cleaned up and sometimes the whole module needs to be changed out .

Anyways, It's plug and play. I'm not 100% if the CRD and V6 gas use the same shift module but I believe they do.

 

@yzjwk
Thanks mate,
I tool a look inside the wk crd shifter assembly and the electronic board inside the shifter is very different from anything found online regarding the the WK's shifters... I'm not sure if its a direct swap

 

@yzjwk
Thanks mate,
I tool a look inside the wk crd shifter assembly and the electronic board inside the shifter is very different from anything found online regarding the the WK's shifters... I'm not sure if its a direct swap

There is no Electronic shift module ( ESM) on the V8 WKs, so they will be different from yours. The FSM seems to indicate that the CRD and V6 Gas ESMs are the same as it makes no distinction between them. Otherwise I know there is no programming involved in a swap.

 

Thanks, I just swap my ESM with an ebay one with the hope of sorting out my issue. After the swap I'm still experiencing the same gearbox/codes behavior ... thought it was due to an unmatched ESM... So I guess ESM is fine there 🤷🏻‍♂️

 

All,
Problem solved😓😓!!
It was a bad "new" conductor plate. Don't buy you conductor plate of Amazon. Bought the "new" new one of Rockauto.

How did I find out? Kept the bad conductor plate hanging underneath connected. Probed with pin N3 & N2 with the oscilloscope. Used a metal piece to swipe over the hall effect sensor to see if there was a signal.

Good signal on the metal sensor.
No signal on the plastic one.

Limp mode is gone now.
Oil temp at operating temp : 82 C ... seems a bit high ... oil type Mobile ATF+4

 

Oil temp is normal , it will match the engine temperature or be about 3-4 deg c below most of the time