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MB S60L AMG W140
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Discussion Starter #1
Hello all MB owners!

I have a problem with my gearbox on a mb S600 96on, five speed transmisson.

LHM is active now. goes only upp to 140km/h until RPM limit hitting. ATF oil found in the Control unit of trany. It kicking when choosing levels between P-R-D and no reactions at all, when selecting 1-2-3-4. Kick down not working.

What i am already did.
1. Diagnostic with special MB tool. it says NO ECU found

2. Cleaned ECU with electronic cleaner and gave it away to an Electricians. He welded it and changed some plates. now it works.

3. Diagnostic with special MB tool again. it says "It says some valves are down and Electronic plate error or somthing like this.

4. ATF Change, harness contact change, oil pan change. No diffrents

5. Changed gearbox to used one and also oil change. Did NOT chenged ECU.

NOW differents at all!
Still in Limb Home Mode.

6. Diagnostic again, Same errors appears. Erase unavailible.

My gearbox is 722.621 that used one i bought is 722.621 comes from a V12 S600 98.

What i am want to do.
Buy another used ECU and renovated transmission from same car. An R129 SL600 1996.

Do you think that will solve my problems?

Please help!!!

93 SL500, 95 SL320, 96 S320, 98 S500, 2002 E320 4Matic Wagon & A little 91 5.0 FORD Mustang
8,064 Posts
Welcome to the forum,

When you make a swap with a used 722.6xx. I find it is best to get the transmission CPU with it, and the shifter. I cannot answer why, but to have a "Plug and Play" experience with no problem. If you can, get the donor Transmission ECU and Shifter.

Now, if you were to rebuild your 722.6xx, it is not a problem.

There are two types of conductor plates. Also the very early 722.6xx use both speed sensors, but the later ones use just one speed sensor.

Maybe one of the solenoids is shorted.

See this video for solenoid impedance values.

Here is the service manual:

More useful data:

All I can say, is Remove the Trans ECU and clean it and let it dry. Replace the connector and O-ring at transmission with factory part . Clean out the cable with contact cleaner, blow-out the cable, and let dry. Then Ohm-out the cable for shorts too.

Best of luck,

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