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:
Checking and adding the
brake fluid
■ Checking fluid level
The brake fluid level should be
between the "MAX" and "MIN"
lines on the tank.
■ Adding fluid
1. Slide and lift up the rubber
strip to partly remove it as
shown.
2. Disconnect the claws and
remove the service cover.
3. Remove the reservoir cap.
4. Add brake fluid slowl ...
Adjustment
1. Headlight aim only
place the vehicle in the following conditions.
The area around the headlight is not deformed.
The vehicle is parked on a level surface.
Tire inflation pressure is in the specified value .
A driver is in the driver’s seat and the vehicle is in a state rea ...
Circuit description
The vapor pressure sensor and the vsv for the canister closed valve (ccv) are
used to detect abnormalities
in the evaporative emission control system. The ecm decides whether there is an
abnormality in the evaporative
emission control system based on the vapor pressure sensor signal.
Dtc p0 ...