/diy/ - Do It Yourself

Can anybody glean how this dosing pump works?

I thought these used PWM to control a specific pressure for the outlet (typically like 120 PSI)

However, ignoring the pressure and temp readings, all there is is the 12V pump power (I'm guessing ON/OFF) and a return valve.

To maintain a specific pressure, is it possible the pump is always on and the return valve is an analog valve that adjusts how open it is?

Or could it be the pump always on, with the return valve turning open/close every few seconds as needed