Theory Of Operation
WARNING: This page is about a different car, the 2019 RAM 3500 HD and 2019 RAM 2500 HD. However, it is still accessible from the selected car via links, so may be relevant.
The Transmission Control Output circuit is used to supply power to the solenoids and pressure switches (Transmission Solenoid/TRS Assembly) when the transmission is in normal operating mode. When the Transmission Control Output circuit is off, no power is supplied and the transmission.
Immediately after a controller reset (ignition key turned to the "run" position or after cranking engine), the PCM verifies that the Transmission Control Output circuits are open by checking for no voltage at the transmission control output terminals at the PCM. After this is verified, the voltage at the pressure switches are checked. There should be no voltage on the pressure switches at this time.