Monitor Description
The idle speed is controlled by the Electronic Throttle Control System (ETCS).
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 Electronic Throttle Control System (ETCS). If the actual idle RPM varies more than a specified amount or a learned value of the idle speed control remains at the maximum or remains at minimum five times or more during a trip, the ECM concludes that there is a problem with the idle speed control ECM function. The ECM will turn on the MIL and a DTC is set.
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 is set.
HINT:
*1: RPM threshold varies with engine load.