I read your post once more.......in my scheme of things, and I could be way off, your pressure switch would have 12 volts wired to it instead of 120 volt motor voltage. When the pressure switch is at it's low cut-in it sends 12 volts to both the flow switch and the timer module. The outputs of both the timer module and the flow switch are connected to the relay (contactor) that controls the pump. No electrical current is passing through the flow switch yet but the timer module has a direct connection to the pump relay. This starts the pump. The flow starts and now the flow switch is conducting electrical current and voltage to the pump relay. The timer contacts disengage after a few seconds but the pump keeps running until the flow switch opens the circuit in a no flow situation. This is called a latch circuit. On the supply side when the pressure builds up again (I am assuming this pressure is supplied from elsewhere) the whole thing starts over again, without you having to GO TO THE WALL SWITCH.