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:

    Inspection
    1. Spark plug Notice: never use a wire brush for cleaning. Never attempt to adjust the electrode gap on used spark plug. Spark plug should be replaced every 192,000 km (120,000 miles). Clean the spark plugs. Air pressure: below 588 kpa (6.0 Kg/cm2, 85 psi) duration: 20 sec ...

    Inspection procedure
    Hint: the switch described in this text is a switch for transmitting signals which is built in the door control transmitter. 1 Check wireless door lock control functions Normal 2 Replace transmitter battery with normal one After replacing the transmitter battery with a new or normal o ...

    Eco drive mode (if equipped)
    Press the switch. Suitable for enhancing the fuel economy, because the torque corresponding to the accelerator pedal depression amount can be generated more smoothly than it is in normal conditions and the operation of the air conditioning system (heating/cooling) will be minimized. Press th ...