Speed Dependent Wipers
WARNING: This page is about a different car, the 2016 Ford Transit-350 HD, 2016 Ford Transit-350, 2016 Ford Transit-250, and 2016 Ford Transit-150. However, it is still accessible from the selected car via links, so may be relevant.
When the wiper/washer switch is in any intermittent setting except the lowest setting, the speed dependent feature increases the frequency of wiping as the vehicle speed increases to compensate for the extra moisture that accumulates on the windshield.
The BCM receives the vehicle speed from the PCM. The BCM activates the windshield wiper on/off relay based upon the vehicle speed.