From a similar vehicle, the Freestyle, some background information that may help you with your Taurus X [The Freestyle end of production drop in...]:
On Freestyle vehicles, the windshield and rear window washers are supplied with washer fluid from a single washer reservoir and pump, which are located in the engine compartment. The Freestyle windshield washer and the rear window washer are activated by their respective internal wiper motor modules when they receive a ground signal from the wiper switch to either the windshield or rear window washer inputs. Voltage polarity is reversed by either the windshield or rear window wiper motor and module assemblies to achieve directional change of the washer pump and washer fluid. Depending on which ground signal was provided, the windshield or rear window wiper internal motor modules activate either the windshield washer or rear window washer internal relays by grounding the respective relay coil. When either relay is activated, it connects voltage to the washer pump while the deactivated relay provides gound to the washer pump.
And some pictures:
Attachment:
FS Washer Reservoir.JPG [ 24.69 KiB | Viewed 88 times ]
Attachment:
FS Washer Reservoir Parts.JPG [ 65.08 KiB | Viewed 88 times ]
Have wiring diagram if needed.