Toyota Celica 2005 Repair Manual page 761

DI−562
DTC P0505
MONITOR DESCRIPTION
The idle speed is controlled by the ETCS (Electronic Throttle Control System).
The ETCS is composed of the throttle motor which operates the throttle valve, and the throttle position sen-
sor, which detects the opening angle of the throttle valve.
The ECM controls the throttle motor to provide the proper throttle valve opening angle to obtain the target
idle speed.
The ECM regulates the idle speed by opening and closing the throttle valve using the ETCS. The TCM con-
cludes that the idle speed control ECM function is malfunctioning if: 1) the actual idle RPM varies more than
the specified amount, or 2) a learning value of the idle speed control remains at the maximum or minimum
five times or more during a driving cycle. The ECM will turn on the MIL and set a DTC.
Example:
If the actual idle RPM varies from the target idle RPM by more than 200 (*1) rpm five times during a drive
cycle, the ECM will turn on the MIL and a DTC will be set.
HINT:
*1: RPM threshold varies with engine load.
Idle Engine
RPM
2005 CELICA (RM1131U)
DIAGNOSTICS −
Idle Air Control System
Target RPM
Actual Idle RPM
Time
760
ENGINE (2ZZ−GE)
Large
Learning Value
of ISC
0
Small
DIC7O−02
Maximum
Minimum
Time
A20597