Corolla LE Sedan L4-1.8L (1ZZ-FE) (1999)
Idle Air Control Valve: Diagnostic Trouble Code Tests and Associated Procedures
CIRCUIT DESCRIPTION
The rotary solenoid type IAC valve is located on the throttle body and intake air bypassing the throttle valve is directed to the IAC valve through a
passage.
In this way the intake air volume bypassing the throttle valve is regulated, controlling the engine speed.
The ECM operates only the IAC valve to perform idle-up and provide feedback for the target idling speed.
DETECTING CONDITIONS
WIRING DIAGRAM
INSPECTION PROCEDURE
HINT: Read freeze frame data using TOYOTA hand-held tester or OBD II scan tool. Because freeze frame records the engine conditions when the
malfunction is detected, when troubleshooting it is useful for determining whether the vehicle was running or stopped, the engine warmed up or not, the
air-fuel ratio lean or rich, etc. at the time of the malfunction.