Theory Of Operation
WARNING: This page is about a different car, the 2014 Fiat 500e. However, it is still accessible from the selected car via links, so may be relevant.
The Door Lock Switch is an internal part of the Door Latch Assembly. It is controlled by the door latch rod connected to the inner door latch handle. The switch supplies a 1000.0 Ohm resistance in the lock position and 0.0 Ohms in the unlock position. The BCM uses that input momentarily and opens the contact to ground on the appropriate lock or unlock driver circuit and supplies 12 volts to that circuit.