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:
Replacement
Hint: components:
1. Precaution
2. Disconnect battery negative terminal
3. Remove seat track upper rail cover rh
4. Remove seat track upper rail cover lh
5. Remove front seat assy lh
6. Remove seat position air bag sensor
Disconnect the connector of the seat position airbag sensor. ...
Brake
On–vehicle inspection
1. Inspect brake line pipes and hoses
Hint:
work in a well–lighted area. Turn the front wheels fully to the
right or left before begining.
check all the brake lines and hoses for:
damage
wear
deformation
cracks
corrosion
leaks
bends
twi ...
On–vehicle inspection
1. Check battery electrolyte level
Check the electrolyte quantity of each cell (maintenance–free battery).
If under the lower level, replace the battery (or add distilled
water if possible) and check the charging
system.
check the electrolyte quantity of each cell ...