IAC Valve Operation
WARNING: This page is about a different car, the 1995 Lexus ES 300. However, it is still accessible from the selected car via links, so may be relevant.
Remove IAC valve. See COMPONENT LOCATIONS under INTRODUCTION. Using a 12-volt battery, connect positive lead to terminal +B of IAC valve. See Fig 1. Connect negative lead to terminal RSC (valve should close), then to terminal RSO (valve should open). Replace IAC valve if it does not operate as specified.