The terminals on the connector are labeled. They are as follows: A-12V, D-ground. B goes to 4th gear pressure switch and C goes to 3rd gear switch.
The 12V source is 'key-on' and normally runs through the brake pedal switch. The computer recieves signals from the two valve body pressure switches.
The TCC solenoid is normally activated by the ECM, or an added switch, grounding terminal D.