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Home >> Toyota >> 2004 >> Sequoia Limited, 4WD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Diagnostics >> Circuit Inspection >> DTC P0505: Idle Air Control System >> Monitor Description

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 sensor, 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 ECM concludes 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 100 (*1) rpm five times during a driving cycle, the ECM will turn on the MIL and a DTC is set.

NOTE: *1: RPM threshold varies with engine load.
Fig 1: Idle Engine RPM Monitor Description
G02921512Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Fig 2: DTC P0505 Chart
G02921513Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002