Toyota 1 MZ–FE Manual page 541

DTC P0505 Idle Control System Malfunction
CIRCUIT DESCRIPTION
The rotary solenoid type IAC valve is located in front of the intake air chamber and intake air bypassing
the throttle valve is directed to the IAC valve through a passage.
In this way the intake air volume bypassing the throt–
tle valve is regulated, controlling the engine speed.
The ECM operates only the IAC valve to perform
idle–up and provide feedback for the target idling
speed and a VSV for idle–up control is also added (for
air conditioning).
Diagnostic Trouble Code Detecting Condition
DTC No.
Idle speed continues to vary greatly from the target
speed.
P0505
(2 trip detection logic)
WIRING DIAGRAM
1MZ–FE ENGINE – CIRCUIT INSPECTION
IAC valve is stuck or closed
open or short in IAC valve circuit
Air conditioner idle up VSV
Air intake (hose loose)
Trouble Area
EG2–541