How do you diagnose if the transmission control module is good in a 1996 Geo Tracker?

Yes it is throwing a code of P0740 and the torque converter is not locking in. At 70mph it's running 4,000rpm

Not understanding your answer. "Be advised stay in one thread-been watching you-" what does that mean?

I am on the same topic. Go through the response, you asked me if it was throwing a code and I answered yes and told you what the code number was. I am asking how you test the torque converter clutch solenoid. As you will see that was my original question and done nothing but answer your questions

Thank you very much that was helpful. Sorry for any confusion.