Toyota Corolla (E120): Circuit description

The rotary solenoid type idle air control (iac) valve is located

The rotary solenoid type idle air control (iac) valve is located under the throttle body and intake air bypassing the throttle valve flows into the iac valve through the passage.

In this way the intake air volume bypassing the throttle valve is regulated, controls the engine speed.

The ecm operates the iac valve only to perform idle–up and provide feedback for the target idling speed.

Monitor description

Monitor description

The idle speeds are determined depending on the volume of air that passes

The idle speeds are determined depending on the volume of air that passes through the iac valve. When the volume is large, the idle speed becomes higher. When the volume is small, the idle speed becomes lower.

The iac valve controls the air volume that bypasses the throttle valve. The engine control module (ecm) sends duty signals to the iac valve and drives the iac valve stepper motor to determine the air volume that bypasses the throttle valve.

Although the ecm regulates the idle engine rpm with the feedback control in several vehicle stopped, actual idle rpm does not reach the targeted rpm and a learned valve angle of the idle air control (iac) remains at the maximum or remains at the minimum, the ecm determines to detect malfunction in the iac system.

Example: if the rpm difference between the targeted and actual idle engine rpms exceeds 200 rpm (*1) with the vehicle stopped in an idle, and this occurs 5 times, or if the learned value angle of the iac remains at its maximum or minimum angle for 5 seconds, p505 is detected.

P0511 is detected as an open/short circuit in the iac if the rate of duty signal input to the iac valve has stuck at 0 or 100 %.

*1: Threshold rpm is varied by an engine load.

Monitor strategy

Typical enabling condition

Typical enabling condition

Typical malfunction thresholds

Typical malfunction thresholds

Component operating range

Component operating range

Wiring diagram

Wiring diagram

Inspection procedure

    Share this page:

    Other materials:

    Fuel system
    Precaution 1. Before working on fuel system, disconnect negative (–) terminal cable from battery 2. Do not smoke or work near an open flame when working on fuel system 3. Keep gasoline away from rubber or leather parts 4. Work for prevent gasoline from spilling out Remove the rear s ...

    Parking brake
    The parking brake can be set or released automatically or manually. In automatic mode, the parking brake can be set or released automatically according to shift lever operation. Also, even in automatic mode, the parking brake can be set or released manually. Operating instructions ■ Using the ma ...

    Dialing by selecting a name
    1 Select “Phonebook” using . 2 Select the desired name using and press the off-hook switch. By pressing (Add S. Dial) and then one of the speed dial buttons (from to ) while the desired name is selected, it can be registered as a speed dial. ...