Air Intake Control Circuit: Description
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.
The air cleaner is equipped with two inlets, one of which is opened or closed by the Air Intake Control Valve (AICV) This system reduces intake noise and increases engine power at low-to-high engine speed range.
When the engine is operating in the low-to-mid speed range, this control operates the AICV to close one of the air cleaner inlets When the engine speed is more than 3600 rpm the ECM turns off the VSV to open the AICV.