System Diagram
WARNING: This page is about a different car, the 2008 Lexus IS F. However, it is still accessible from the selected car via links, so may be relevant.
Various switches or sensors are represented as inputs for the different systems mentioned in the article Where direct electrical connections do not exist between components, signals may be carried across the different networks (BEAN, CAN) that exist on the vehicle If a signal needs to travel from a CAN system to a BEAN system, the gateway ECU allows the signal to travel between these different networks. Some of these different signals can be confirmed or inspected using the Techstream