A vehicle or other system includes an actuator assembly operable to achieve a selected operating state of the system in response to an electronic state selection signal, a push-button shifter assembly, and a controller. The shift assembly includes push-buttons, each including at least three redundant switches. A binary open/closed state of each switch defines the electronic state selection signal. The controller is in by-wire communication with the actuator and push-button shifter assemblies, and receives the electronic state selection signal. The controller determines a pressed, released, or unknown button state of each push-button by determining, in response to the electronic state selection signal, if all of the redundant switches have closed. If all of the redundant switches have not closed, the controller determines whether fewer than all of the switches have closed and opened within a calibrated time interval of each other.