Where is the Torque converter clutch located?

It is inside the torque converter. Not a serviceable part. You replace the torque converter as a unit. What is the issue you are having?

The OD light flashing means the transmission control module sees a problem. Then you use a scan tool to read the codes and combine that with the symptoms as well to diagnose the problem. It could be a solenoid, but it could also be an internal clutch. The solenoid assembly is inside the transmission as well. You would drain the transmission, then remove the pan, filter and then depending on which transmission you have, you would remove either the solenoid block or the valve body. That gets changed out with the replacement and then it all does back together. Once done you use a scan tool to test them again. If everything is okay, you are done.

It is inside the transmission as part of the solenoid block assembly. Yours should have the units pictured for the 4R70W transmission. Parts # 6L3Z7G484A is the first solenoid block, # F8AZ7G136AA is the TCC solenoid. You will also need the fluid and a new filter. You drop the pan off then the filter and if you look up into the transmission you will see the solenoids as circled in the third image. The main block is held in with 2 bolts, one of them also holds the TCC solenoid so that you have to remove both to get the TCC out. Because of that I tend to replace both as well as the filter as they all need to come out and they have the same mileage and wear. You will also want to inspect the lead frame (wiring harness) for loose pins or damage. The pins can become loose.

This video covers that pretty well:
https://www.youtube.com/watch?v=O9Rxch3zHHM

This one shows more of the process to replace them:
https://www.youtube.com/watch?v=GiJmwX0Mbm0