Theory Of Operation
WARNING: This page is about a different car, the 2016 Dodge Durango. However, it is still accessible from the selected car via links, so may be relevant.
The Body Control Module (BCM) provides a reference voltage on the wiper park switch sense circuit through a pull - up resistor that is connected to battery voltage. The Wiper Park Switch switches the signal circuit to ground when the wiper motor is in the park position.