Circuit Description
This electrical throttle system does not use throttle cable. Throttle position sensor is mounted on throttle body and has 2 sensors to detect throttle opening angle and any malfunction of throttle position sensor. Voltage applied to terminals VTA1 and VTA2 of ECM changes between zero volts and 5 volts in proportion to opening angle of throttle valve. VTA1 is a signal to indicate actual throttle valve opening angle which is used for engine control, and VTA2 is a signal to indicate information about opening angle which is used for detecting a malfunction. ECM judges current opening angle of throttle valve from these signals input from terminals VTA1 and VTA2, and ECM controls throttle motor to make throttle valve angle correct in response to driving condition. When a malfunction is detected, throttle valve is locked at a certain opening angle. Also, electronically controlled throttle operation is cancelled until system returns to normal and ignition switch is turned off. See Fig 1.