w210 transmission fluid migration and TCU
 

Does anyone have a link to a thread or HOWTO that discusses this issue? Specifically I'm looking for 1. how to check whether or not you have this problem. and 2. what the fix for this is.

This is for the issue where transmission fluid migrates up the wiring harness and into the TCU, toasting it.

Thanks

I can see the Smoke...(From the Fire)
 

Pardon my memory,if it's faulty...But I believe the long term remedy was to replace to rubber sealing o-ring on the wiring sub harness.


Almost the discussion you want:
http://www.peachparts.com/shopforum/diesel-discussion/222123-transmission-failure-99-e300td.html?highlight=w210+transmission+fluid+migration+TCU

AND:
member jvmaxime may have your solution in reply #12 to this post:

http://www.peachparts.com/shopforum/tech-help/247499-97-s420-transmission-trouble.html?highlight=w210+transmission+fluid+migration+TCU

Transmission Data plug/Pilot Bushing/Electrical plug info
 

Here are some links. The first is how I caught mine JUST in time, the second, a "How-To" with some pretty good pics.

http://www.peachparts.com/shopforum/diesel-discussion/249272-change-thy-data-plug.html

http://www.installuniversity.com/mb/w203/w203/trans_oring.html

Yes, when I did mine a couple of months ago the dealer stocked the complete assembly, not just the replacement o-rings like they used to sell. The parts counterperson told me the part had been redesigned (for the third time) and now they only sell the complete plug assembly - it only costs $7 and will save you lots of time and trouble. Mine leaked originally and was replaced, and leaked again at this last change...now, hopefully, the new plug will last longer.

This is perfect, thanks everyone. :)

Changed mine out today thanks to the informative links and pics. A pretty simple job. My connector was leaking apparently as I got a bit of fluid coming out when I undid the plug.

Upon replacing the socket, I noticed that the old leaky one had black O rings, just like the new replacement. I was expecting to see red or white O-rings...

I wasn't able to locate the TCM in my car to check for fluid at that end. Anyone know where the TCM is on W210? I opened the electronics box on the side of the engine bay, and there's a lot of stuff in there but nothing that had sealed connectors on it. Loads of wires, all of them looked dry, no fluid.

Excerpt from:

http://www.peachparts.com/shopforum/2170298-post12.html

"I went to locate the TCM (transmission control module). It is under the hood inside a black box with a yellow sticker that said Battery in trunk. As soon as I removed the harness to the left of the module, I notice ATF at the connector. "

Unfortunately that fellow's car is an S420. Not a w210 chassis. I did check just in case though, and I have no black boxes with yellow stickers that say "Battery in trunk"...

I did check inside the black electronics box (where the K40 relay lives) and didn't see a module that looked like the one in that thread.

According to the EPC it is in the box that houses the ECM for the engine, brakes, etc...look for these PNs.

Perfect, thanks!! :) I'll take another look...