Unsure if you've moved forward or not but I will also say that the tcm is indeed built into the valve body and the valve body is likely the issue. I have a 2016 Mazda 6 and the tcm is on the fritz. It will throw at, parking brake, engine, traction control lights randomly, go into limp mode randomly, and have the start button flash red and refuse to start occasionally. Every code, from engine light to the abs code is all tcm failure or lost communication with tcm. And it is an entire valve body and tcm assembly that needs replaced. I've reset the transmission, I've unhooked the battery, ECT. It'll drive fine for a week then freak out again. I even replaced abs sensors in case they were reading improperly and confusing the computer. My Mazda dealer says they've never replaced a valve body or tcm in these cars but can do it. Aamco says they can do it as well. The issue is it will need programmed to the vehicle it is installed in. They are vin locked. It can be replaced without replacing the entire transmission. I attached photos of the codes I have, if you don't have similar codes I don't think it'd be your tcm necessary. .