Start-Stop Switch
WARNING: This page is about a different car, the 2013 Ford Escape. However, it is still accessible from the selected car via links, so may be relevant.
The start/stop switch is a momentary contact switch that is hardwired to the RFA module, BCM, and PCM. When the switch is pressed, it signals the RFA module, BCM and PCM there is a request to either switch the ignition on or start the engine. The start/stop switch is connected to both modules as a backup in case of a failure. If there is a circuit failure to either module from the start/stop switch, the modules communicate the start/stop switch request to each other over the MS-CAN.