crconsulting

That’s where to start looking. Chances are it’s only one of those solenoids.👍

crconsulting

Just came across the class notes on 722.9 I was looking for….
see attachment:

Keep us posted,

Good Luck

JettaRed

iTrader: (1)

I actually found the valve body from my 2004 SL500 with the valves installed. It was all wrapped up when I asked for it back from the dealer and never opened it. The part number is 2202770901, which doesn't match the EPC. So, I am wondering if the valve body, which has no electronics that I am aware of, is interchangeable.

crconsulting

Disclaimer: I have never been, or wanted to be “The Tranny Guy” in the shop. Working on slush boxes was always my least favorite job, followed closely by working on hydraulic suspensions such as ABC. But as I remember it,

Theoretically it should work, but…..
The reason why Mercedes sells only complete valve bodies, and needs an old TCU to rewrite data to a new one (if only TCU is to be replaced) is the factory calibration of the entire valve body with solenoids.

This procedure takes place at the factory, on a test bench, and is designed to measure oil pressure rising when the solenoids are actuated by increasing (or decreasing) current and to save the values permanently in the TCU. If the expected values deviate from the measured values, the calibration curves of individual solenoids should be corrected.

Calibration vs. adaptation: Adaptation is dynamic and changes depending on the wear of the gearbox components. Calibration is a constant (by the factory) and is a pre-requisite for proper adaptation.

Each solenoid can have up to 12 different factory tolerance settings and all of them must be precisely calibrated to ensure hydraulic balance of the whole valve body.

There are not only 2 different valves (blue and black top), but at least 12x8 different variations of current/pressure reactions.
Replacement of hydraulics or solenoids, and even swapping of solenoids with each other places, can irreversibly affect the operation and adaptation of the gearbox, and transmission life expectancy.


Good Luck

jakubmomentum

Thank you
yea there’s a ton of room for error. I just have to try what I can to fix it.

crconsulting

Exactly, unfortunately the best trial and error approach now, is to make only one solenoid change at a time in the circuits that control that 2-3rd shift.
It's ugly, but if you start swapping out multiple solenoids at once, or put another valve body in there, you can get buried quick.

I think you're close, since you're not triggering any codes and not going into limp mode.

Keep us posted.

JettaRed

iTrader: (1)

You know, the last one that gets changed fixes the problem, don't you? Let's hope the last one he changes is the first one to fix the problem.

It's gonna be a tedious job!

JettaRed

iTrader: (1)

So, would my valve body with the valves installed make a difference with a different conductor plate? Are there changes between the valve bodies for the 1st gen and last gen 722.9 trannies? Just didn't know if the little tunnels, etc. were different sizes.

crconsulting

Knowing MB, you can bet there are revisions made to the valve body over the years. Are they interchangeable without issues? I can’t tell you for sure (I would think most are reliability related), but to give you an idea, these are just some part numbers associated with that casting

A 2202701306
A 2202770801
A 2202771301
A 2202771401
A 2202770901
А 2312700060
A 2312703501
А 2312700160
A 2312700460
A 2312703501
A 2312700460
А 2302706800
А 2302706900
А 2302707000
A 2302708200
А 2302708100
А 2302707100
А 2312705100
A 2312703601
А 2302708000
А 2302700506
А 2302700606
А 2302700160

crconsulting

This may help too

see WIS attachment: AR27.19-P-0212A Remove/install control solenoid valves

crconsulting

Did you get it shifting properly?