The 'Stang's factory ignition switch assembly is attached to the steering column. With the switch disconnected, Mase uses a Scotch-lock and links the primary wire from the push-button switch's harness (yellow) with the green wire on the OEM switch. When connected in this fashion, the engine actually can still be started with the key. To restrict the engine to being started only with the button, the green wire must be cut. When this plug-and-play operation is finished, Mase reconnects the battery and tests both new systems to confirm they're functioning properly and all trim panels are reinstalled.