Circuit Description
WARNING: This page is about a different car, the 2004 Lexus IS 300. However, it is still accessible from the selected car via links, so may be relevant.
This circuit opens and closes the Intake Air Control Valve (IACV) in response to the engine load in order to increase the intake efficiency.
When the engine speed is 4,300 RPM or less and the throttle valve opening angle is 30° or more, the ECM turns the VSV ON and closes the IACV. At all other times, VSV is OFF, so the IACV is open.
HINT:
IACV stands for "Acoustic Control Induction System".