Hi guys, I just spend a better part of the day working with the 722.6 valve body on my 02 XKR, now topped her off, started, and she's not happy. I could really use some help here...

Original Symptoms:
i) P0716 Speed Sensor error
ii) Dropping to neutral
iii) harsh shifts, shifts "slipping"
iv) Occasional "Transmission Fault" message

Diagnosis:
i) Checked the MB forum, apparently P0716 is a common issue on the 722.6 remedied by a new conductor plate (which includes a speed sensor).
ii) Slipping issue commonly remedied by a Sonnax valve body valve sleeve kit. Recommended to also change connector plug, and obviously perform a flush with a new filter.
iii) Optional step is some take this opportunity to install the MB Blue tops solenoids for firmer shifts.

Process:
I mainly followed the procedure outlined here:
Photo DIY- 722.6 Conductor Plate and Regulator Valve Spring R/R - Benzworld.org - Mercedes-Benz Discussion Forum
In addition, I installed new MB blue tops solenoids instead of the old brown tops.

i) I drained the ATF fluid, dropped the pan, removed valve body
ii) Replaced conductor plate
iii) Replaced brown top solenoids with new solenoids. Made sure all other solenoids installed in correct locations.
iv) Installed the Sonnax valve sleeve kit. Old sleeves slid right out, had wear marks. New sleeves have an o ring, and went in snug. Installed plunger and spring per directions and stock configuration. Triple checked that all sleeves were in their correct respective locations, and installed per directions.
v) Checked all the springs in the valve body for breakage or wear. Valve sleeve springs were checked via micrometer for correct length, and they are in spec.
vi) Valve body was reinstalled.
vii) Connector plug was replaced, connector inserted and tigtened.
viii) ATF filter installed on valve body
ix) Pan reinstalled with new gasket
x) Old fluid drained (including from filter) precisely measured at 3.15 liters
xi) 3.15 liters of new Shell ATF 134 fluid filled. MB tranny dipstick reading shows same as before repair, and meeting minimum level requirement at cold.
x) Battery disconnected, leads touched to "reset"
xi) Car started. Issues immediately apparent:

New Symptoms:
i) "Transmission Fault" message, "Transmission High Temp" message
ii) P0740 Torque converted Clutch Circuit Open
iii) P0753 Shift Solenoid A Electrical
iv) P0758 Shift Solenoid B Electrical
v) P0763 Shift Solenoid C Electrical

Shifter shifts between all gears, park OK, in drive the car limps forward (feels like starting in 3rd gear), in reverse the car reverses. Limping good enough to drive from garage to driveway, but not driveable at the moment.

Is there something I'm missing here guys?
Is the mix of codes I'm getting indicative of a particular step of the process I could have messed up?
Anyone else with the Sonnax valve sleeve kit installed, or experience with it?
For those of you with blue tops, did you ever have issues like these during install?

Any help would be greatly appreciated!

 

With four electrical "open" faults, the first place to look would be first the sleeved connector at the right front corner of the transmission on the exterior. That would be easy. Otherwise, the inside end of that connector and the conductor plate.

It doesn't sound like any damage has been done. You just have more work to do.

When filling, don't forget that some has dribbled out from the valve body and other parts. It is more reliable to fire it up to fill the passages and then fill to spec using a dipstick measurement.

Are you sure the Sonnax sleeve thing is the the Merc? I thought that was a ZF thing.

How much were the blue tops for the pair?

 

Thanks for your reply Plums, the connector does sound like the logical place to start.

Sonnax makes kits for a lot of units, but this sleeve kit is for the 722.6. The diagram matched the valve body I took out of the XKR perfectly, down to specs like free lengths on the multiple valve body springs, which were checked. Per the kit's instructions, I assessed the stock sleeves which had "shiny" parts and signs of wear indicative that they need replacing. I have pictures from this process and will post those up soon.

I will try filling the fluid/draining/filling/checking as well.

Blue tops were from Parts.com for $160 each, which is the best deal I have found around.

Thanks again!

 

Hopefully it's the external harness connector. Also look for fluid wicking up the harness which is why the connector gets replaced to begin with.

You may also want to seal the seam of the dipstick tube where it meets the transmission case with silicone RTV.

A Chrysler TSB for slippage on the NAG-1 states that as little as 0.5 percent water in the fluid will cause slipping and other weirdness. The cure is sealing the dipstick tube with RTV followed by 3 drain and refills. The tube does not come out, you just clean the area and smear RTV on the outside of the seam. Really awkward spot when on the ground though. As you know, the NAG-1 is the same transmission under a different name.

 

Question, did you disconnect the battery prior to you doing any work on the trans? If not do a hard reset.

 

Good news guys, issue solved!

The electrical connector wasn't in all the way. I noticed it seemed to have a little bit of movement in it even though the sleeve ring was tightened. Well, after messing around with it gently for literally almost an hour, it finally clicked in it's right place, I tightened the sleeve ring, did a hard reset, and all's good! I had to get my gloves off and really feel it click in, man, this thing was a puzzle.

I did about 40 miles to test everything and all looks good, no codes, shifting is nice and firm (with a nice kick, no doubt thanks to the blue tops), and I don't feel it slipping through shifts anymore. Looks like Christmas came two days early for me!

 

Don't you just love it when things just 'click'

So you're next up for a "long term blue tops in sport mode" review?

 

I've taken plenty of pictures and will be writing my transmission adventure up in the next little while. So far everything looks good, but I want to give it a few more miles and cycles to make sure nothing's up. I'm loving the blue tops so far, shifts are quick and firm, and the up and downshifts are more noticeable, but not too harsh at all in my opinion (as some reviews online make them out to be). Will keep you guys posted!

 

Getting ready to take on the same work. I have already purchased the conductor plate and connector sleeve. I have been getting the same codes with gear box fault message. This post was very timely for me. Thank-you I will watch to ensure I get the click.

I have not read anything on the blue top solenoids. What is the reason for replacement?

Did you disconnect the battery for this work?

 

Whew! Great news! I was wondering what could have gone so wrong.

Thanks for the feedback on the blue-tops...they definitely look like a compelling upgrade.

 

Kudos to you! On the road again!

 

Old post.. but what conductor plate did you go with? (part number) I'm thinking of replacing it while i'm in there for the hell of it.

 

I went with an MB factory 722.6 conductor plate off ebay, for about $125.

like this:
Mercedes Benz Transmission Electrical Conductor Plate Genuine Original 722 6xx | eBay

Very easy to replace and a common wear component from the reading I've done on MB forums!