General Procedure

Cycle and park the rear window wiper.
Verify the rear wiper blade is positioned at the first defroster line located on the rear window glass.

Fig 1: Locating Wiper Blade And Pivot Arm (Rear Window)
Courtesy of FORD MOTOR CO.
If necessary, remove the rear wiper arm using a gear puller, position the rear wiper pivot arm and blade and align the blade tip to the first defrosting line.