Circuit Description

WARNING: This page is about a different car, the 1995 Lexus LS 400. However, it is still accessible from the selected car via links, so may be relevant.

Idle Air Control (IAC) valve is a step motor type and is located on air intake chamber. Intake air by-passing the throttle valve is directed to IAC valve through a hose. This allows air volume by-passing the throttle valve to be regulated. Code is set if idle speed continues to vary greatly from target speed. Possible causes are:

IAC valve stuck or closed.
Open or short circuit in IAC valve circuit.
Vacuum Switching Valve (VSV) for A/C idle-up.
Air intake hose.