Theory Of Operation
WARNING: This page is about a different car, the 2016 Dodge Journey and 2015 Dodge Journey. However, it is still accessible from the selected car via links, so may be relevant.
The Body Control Module (BCM) provides a ground path for the wiper park switch sense circuit through a pull-down resistor that is connected to ground. The Wiper Park Switch switches the signal circuit to voltage when the wiper motor is active and in the park position.