Circuit Description

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

The ECM operates only Idle Air Control (IAC) valve to perform idle-up and provide feedback for target idling speed. A Vacuum Switching Valve (VSV) is added for idle compensation when A/C is operated. Code is set when idle speed continues to vary greatly from target speed. Possible causes are:

IAC valve stuck or closed.
IAC valve circuit open or short.
VSV for A/C idle-up.
Air intake leak.