Circuit Description
WARNING: This page is about a different car, the 2003 Lexus GS 430. However, it is still accessible from the selected car via links, so may be relevant.
Idle speed is controlled by Electric Throttle Control System (ETCS). ETCS is composed of the throttle motor to operate the throttle valve, the magnetic clutch to connect the throttle motor with the throttle valve, the throttle position sensor to detect the opening angle of the throttle valve, the accelerator pedal position sensor to detect the accelerator pedal position, the ECM to control the ETCS and the one valve type throttle body. The ECM controls the throttle motor to make the throttle valve opening angle properly for the target idle speed. DTC is set when idle speed continues to vary greatly from target speed. Possible causes are:
- Faulty air induction system.
- Faulty electric throttle control system.
- Faulty electric throttle control system circuit.
- Faulty PCV piping.
- Faulty ECM.