SL/R230: TCM swap out
Thread Starter
Newbie
Joined: Nov 2025
Posts: 5
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2004 sl500 and 1999 slk 230k
TCM swap out
Thank you for your reply so that option appears to be a non starter so im now going to replace the solenoids in my own unit in the hope that will work.
thanks again
thanks again
Super Member
Joined: Sep 2021
Posts: 537
Likes: 115
From: Ann Arbor, MI
2004 SL600
The many transmission codes you listed the other day sounds more like the entire trans is disconnected or the TCM had a total failure. As mentioned, trans fluid can seep up the harness into the TCM and damage it. This does not sound like bad solenoids. For one, not every one would fail at once.
Super Member
Joined: Sep 2021
Posts: 537
Likes: 115
From: Ann Arbor, MI
2004 SL600
In any case, the OP's extensive list of transmission codes does not indicate problems with the solenoids. Either the harness is disconnected, a fuse related to the TCM is blown, or a major computer malfunction in either the TCM or the "chip" in the conductor plate.
To guess (!) I suspect the conductor plate. I have no idea who, other than a dealer, can program a replace plate, but I suspect various independent tuning shops can do it, perhaps even sell a pre-programmed plate.
