Circuit Description
WARNING: This page is about a different car, the 2003 Lexus IS 300. However, it is still accessible from the selected car via links, so may be relevant.
Battery positive voltage is supplied to terminal +BM of ECM even when ignition switch is off for electric throttle control system. If malfunction is detected, ECM shuts down power for throttle motor, and throttle valve is fully closed by return spring. Throttle valve is locked at a certain opening angle. Also, all electronically controlled throttle operation is cancelled until system returns to normal and ignition switch is turned off.
DTC is set when there is an open in ETCS power source circuit. Possible causes are an open in ETCS power source circuit or faulty ECM.