Washer Pump
WARNING: This page is about a different car, the 2013 Ford Explorer. However, it is still accessible from the selected car via links, so may be relevant.
The front and rear washer system share the same washer reservoir and a bi-directional washer pump. The pump delivers washer fluid to the rear glass when the windshield wiper motor activates the rear washer relay, which provides voltage to the washer pump. Ground for the washer pump is provided through the washer relay which is internal to the windshield wiper motor.