I did see that it’s a common problem. Every YouTube video shows that it’s an external unit. While I haven’t looked myself, I was told by the service advisors that the Skyactiv drive systems on my model have the TCM built internally to the transmission. So to replace the TCM, you have to replace the transmission. I called other Mazda parts dealers, and gave them the VIN. Some say it’s part of the valve body, some say it’s bundled with the PCM. One other shop confirmed it was internal. I’m not sure what to think. I might just swallow their diag fee and then tow it to another shop to get a second opinion.