1. Pull the stalk towards you: This usually engages the rear wiper in a single sweep.
2. Push the stalk and hold: Some Windstars might require holding the stalk in a certain position to continuously operate the rear wiper.
If neither of these works, your rear wiper motor may be malfunctioning, the fuse might be blown, or there could be a problem with the wiring. Check your owner's manual for specifics regarding your model and for troubleshooting steps.