Intelligent Switching Unit (ISU)
WARNING: This page is about a different car, the 2006 Suzuki Verona. However, it is still accessible from the selected car via links, so may be relevant.
Because the conventional electric systems, in which simple timers, relays and individual control units are used, have separate circuit for each system, they require a lot of components as well as complex wiring. But ISU does not need such things because it integrates such complex units and wiring into a micro-controller and also controls itself intelligently.
By doing that, the number of components gets smaller and the wiring simpler, in addition, the diagnostics of electrical systems easier by using the scan tool.