Toyota Corolla (E120) 2002–2008 Repair Manual / Diagnostics / Sfi system / Idle air control System/ Circuit / Circuit description
Toyota Corolla (E120): Circuit description
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
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 malfunction thresholds
Component operating range
Wiring diagram
Other materials:
If the shift lever cannot be shifted from P (except vehicles with a manual transmission)
If the shift lever cannot be shifted with your foot on the brake pedal, there
may be a problem with the shift lock system (a system to prevent accidental operation
of the shift lever). Have the vehicle inspected by your Toyota dealer immediately.
The following steps may be used as an emergency ...
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1. Notice about vehicle condition when jacking up
As a rule, the vehicle must be unloaded when jacking up. Never jack up
or lift up the vehicle loaded
with things of heavy weight.
when removing any parts of heavy weight like the engine and
transmission, the center of gravity of
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On–vehicle inspection
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check the slide opening operation (manual).
Turn the ignition switch on.
When keeping operating the sliding roof switch to the open side,
check that the roof glass will
slide and be fully opened.
check the slide closing ...