Circuit Description
WARNING: This page is about a different car, the 2002 Toyota MR2. However, it is still accessible from the selected car via links, so may be relevant.
Throttle valve opening angle is detected by Throttle Position (TP) sensor and sends a signal to ECM. ECM then uses this signal to control throttle control motor which opens and closes throttle valve in response to driving conditions. If DTC P1633 is present, ECM turns off power to throttle motor and magnetic clutch, and throttle valve is fully closed by return spring. When this occurs, opening angle of throttle valve is controlled by accelerator pedal by means of a throttle cable. Possible cause is defective ECM.