Idle Speed Control Motor (DC Motor)

Operation

The volume of intake air during engine idling is controlled by the opening and closing of the IAC valve for bypassing the throttle valve, located at the air intake port.

The IAC valve opens and closes depending on whether the DC motor inside the idle air control motor is turning clockwise or anti-clockwise. The DC motor turns clockwise or anti-clockwise according to the change in the direction of current in the motor drive IC inside the engine control module.


Troubleshooting Hints

Hint 1: While the engine is idling, if the idle speed and IAC valve position (step) change when the air conditioning switch is turned to ON and OFF, it can be assumed that the idle air control motor and the IAC valve position sensor are operating normally.

Hint 2: If the IAC valve position (step) is outside the standard position, the malfunction is probably one of the following:

(1) Basic idle speed adjustment is wrong
(2) Some deposit is adhering to the throttle valve.
(3) Air is being drawn into the air intake manifold through a defective gasket seal.
(4) EGR valve sheet adhesion is defective
(5) Combustion malfunction inside a cylinder. (Spark plug, ignition coil, injector or compression pressure is defective.)




Harness Inspection

Actuator Inspection

Use a sound scope to check if the sound of the idle air control motor operating can be heard immediately after the ignition switch is turned to "ON".

NOTE: If the sound of the servo operating cannot be heard, check the motor drive circuit and the idle air control motor.