Description and Diagnostic Procedure

SYSTEM: Idle Air Control Valve Circuit

CIRCUIT DESCRIPTION



The Idle Air Control Valve is provided on the intake air chamber and intake air bypassing the throttle valve is directed to the idle air control valve through a passage.



A step motor is built into the idle air control valve. it consists of four coils, a magnetic rotor, valve shaft and valve. When current flows to the coils due to signals from the ECM, the rotor turns and moves the valve shaft forward or backward, changing the clearance between the valve and the valve seat.
In this way the intake air volume bypassing the throttle valve is regulated, controlling the engine speed. There are 125 possible positions to which the valve can be opened.


DIAGNOSTIC PROCEDURE



1. CHECK OPERATION FOR IDLE AIR CONTROL VALVE.
^ If OK proceed to step 2.
^ If not OK replace idle air control valve.

2. CHECK HARNESS AND CONNECTOR BETWEEN THE EFI MAIN RELAY, IDLE AIR CONTROL VALVE AND ECM.
^ If OK proceed to "Diagnosis By Symptom".
Symptom Related Diagnostic Procedures
^ If not OK repair or replace harness or connector.