722.6 Shift from 2nd to neutral

[Roncallo]

I have read various posts and saw a few recommendations on similar situations. I have a 1996 SL600 which was received as a wreck. I do not know how well the transmission performed prior to or right after the wreck. But after servicing this trans and reinstalling it it now shift's from second to neutral, when trying to shift to third. Stays in neutral until you slow down long enough to get it to down shift.

In accordance with previous posts.
Checked and adjusted fluid level.
When the trans was out of the car there was evidence of oil wicking into the connector that was cleaned and a new material (white, old one was red) seal was installed.

Examination of the power flow for this transmission indicates to me that the K2 clutch is not engaging. Using Carsoft 7.4 software I get no EGS codes.

Considering each time I pull the pan on this it's $100.00+ I would like to get your thoughts. Should I pull transmission and do a complete overhaul or maybe pull valve body and replace 2-3 shift solenoid. Can I do a pressure check of the K2 clutches with the VB removed.

I am very familiar with overhaul of automatic transmissions in American cars only. But I've yet to do an MB. I can think of three sources of manuals for overhauling transmissions. Does anyone have anything more appropriate.

MB 129 service CD
ATSG Transmission manuals
All Data

Your thoughts

[porkface]

http://www.auto-video.com/ go here and but the 722.6 package they have. i've not done any rebuilds myself, always buy them. just a valve body here and there. i can't say why the 2-3 shift is doing that. never seen that in a 722.6 good luck, chuck.

[stevebfl]

I think you better tell it how fast you are going. Why the H would it shift when you aren't even moving.

[Roncallo]

Originally Posted by stevebfl

I think you better tell it how fast you are going. Why the H would it shift when you aren't even moving.

All 4 wheel speed sensors are installed. It is shifting but unfortunately its shifting into neutral. But that is a good point Tomorrow I will check the wheel speed sensors with the live data function to see that they are working properly.

I did more testing today with live data. It appears to not be getting a command to shift. This also happens whether I start in W (second gear start will go from 2nd to neutral) or in S (first gear start will go from 1st to neutral). The command to shift is never given but neither is the command to go into neutral. The transmission will just hold its gear either first or second at long as it is under acceleration. The sift to neutral occurs at a time that the transmission would normally up shift like when you let up on the gas or just attain a high enough speed.

[iwrock]

http://www.peachparts.com/shopforum/tech-help/145652-722-6-transmission-issue.html#post1098330


E420 Transmission Control Problems

[Roncallo]

Originally Posted by stevebfl

I think you better tell it how fast you are going. Why the H would it shift when you aren't even moving.

Steve you nailed it. Last week when I was installing my yaw rate sensor and lateral accelerometer, I had to disconnect the wheel speed sensors at the pass through connection. When I was done, with the wires laying in place and looking like they were connected from 5 ft away I forgot to reconnect. After responding to your post last night I remembered that I had to disconnect those. I went right over to the car and sure enough they were not connected. Connected them took the car for a drive and no problems so far.

I haven't gotten much over 30 mph yet due to rain but I so far got 1st second and third no limp home mode no problems yet. This car without ESP in the rain can get away in a heartbeat so I have to be real careful.

Thank you Steve

Most transmission shops around hear probably would have charged me $4000.00. Just one more example of the value of these boards.

[Roncallo]

Originally Posted by iwrock

http://www.peachparts.com/shopforum/showthread.php?p=1098330


E420 Transmission Control Problems

Thanks Justin

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