Es300, GS300, GS430, GX470, Is300, LS430, Lx470 & SC430
ETCS consists of throttle body, accelerator pedal position sensor, Throttle Position (TP) sensor, throttle control motor, magnetic clutch and Engine Control Module (ECM). ETCS uses ECM to calculate throttle valve opening in throttle body in relation to driving conditions. ETCS controls idle speed control system and cruise control system operation. On ES300, GS430, GX470, LS430 LX470 and SC430, accelerator pedal position sensor is mounted on accelerator pedal. On these vehicles, there is no throttle cable. On GS300 and IS300, accelerator pedal position sensor is mounted on throttle body and is integrated with throttle lever, which attaches to throttle cable. See Fig 1. Accelerator pedal position sensor converts amount of accelerator pedal effort into 2 different types of output signals and delivers input signals to ECM. TP sensor delivers input signals to ECM to indicate throttle valve opening.
ECM uses these input signals to operate throttle control motor for following: proper operating speed in relation to accelerator pedal position, engine speed to obtain proper idle, and to set throttle valve position for cruise control operation. Throttle control motor operation is also tied in to traction control system. Throttle control motor is mounted on side of throttle body, and operates throttle valve on throttle body by use of a magnetic clutch.
In case of an ETCS malfunction, Malfunction Indicator Light (MIL) on instrument panel will be illuminated and Diagnostic Trouble Code (DTC) will be stored in ECM. If malfunction exists, magnetic clutch will be disengaged, allowing spring pressure to close throttle valve. When magnetic clutch is disengaged, throttle control motor will not operate throttle valve. If ETCS is shut off, accelerator pedal may be used to operate throttle valve for vehicle operation in limp mode by using limp mode lever on throttle body to operate throttle valve.