For 1990-2009 cars

The rear wiper and rear wash button is located on the instrument panel below the climate control system.

(Rear Wiper): Press to turn the rear wiper on and off. The wiper speed cannot be changed.
(Wash): Press to spray washer fluid on the rear window. The window wiper will also come on. Release the button when enough fluid has been sprayed on the window. The rear wiper will run a few more cycles after it is released. If the rear wiper function was already on, prior to pressing the wash button, it stays on until the wiper button is pressed again.

The rear window washer uses the same fluid that is in the windshield washer reservoir. See Windshield Washer Fluid .