Conventional Ignition Switch: Start

When the ignition switch is placed in the start position, the switch routes voltage through the RUN-designated and START-designated circuits to the BCM  . The BCM  interprets this as the ignition start state and communicates the ignition mode to the other modules by sending an ignition status message over the CAN 

Additionally, the ignition switch routes voltage to the PCM  indicating a request to start the vehicle.