2013 Forte EX transmission problems


New Member
As stated in the title, this car is having problems with the transmission. (or so I thought)

Here's the history. 2.0L, 6spd auto. Bought new, one owner, 120k miles. Perfect operation; no problems. Oil changed regularly, etc.
About 1k miles ago, it started shifting oddly. Start off in 1st, changes to 2nd OK. 2nd to 3rd, it revs higher than normal, but finally will get into gear. Same from 3rd to 4th and 4th to 5th.
It finally gave a code of P0741: Torque Converter Clutch Circuit → Performance or Stuck Off But then promptly goes away.
I called around to some shops and they were saying anything from "we can diag it, to we can change the solenoid, to you need a whole new/rebuilt trans", ranging from $500 to $2600.
Based on everything that I have read, I decided to go ahead and source a low mileage one from a yard. Found one with ~18k miles on it and did the swap (w/ new oil). Yes, it was less than the $500.
That did nothing to change the behavior. Same shifting problems.
I have tried to find info on where the TCM is, but nothing has came up yet.
Is it integrated in the ECM?
Help, please. Thanks.