Also, there in the wiring going into the transmission there are at least 8 Wires entering the socket for the wiring harness that enters the transmission.

Check there for connection to the PCM as well as all other paths.

Occasionally, there does exist Transmission Control Relay/Solenoid between the wires and their end location at the PCM harness boot.

Should the Relay/Solenoid fail, then there would no longer be proper communication between the Transmission Control System inside the PCM and the actual solenoids or sensors inside of the transmission which control the different functions of the transmission.

Investigate within these areas for a possible aid.