When I wanted daylight running lights, I used the one lead in question off the fuel pump relay to simplify wiring. (darned near wired itself, if I might brag).

The relay, and computer work together to detect the distributor contacts opening and closing, or being still. If they are still, the pump runs only a moment or two each time you move the key to "run". Obviously if the computer is seeing the engine turning over (no minimum RPM, just turning over) it runs continually.