Throttle Position Sensor: Description and Operation

CIRCUIT DESCRIPTION
The throttle position sensor is mounted in the throttle body and detects the throttle valve opening angle. When the throttle valve is fully closed, the IDL contacts in the throttle position sensor are on, so the voltage at the terminal IDL1 of the ECM becomes 0 V. At this time, a voltage of 0.3 ~ 0.8 V is applied to terminal VTA1 of the ECM. When the throttle valve is opened, the IDL contacts go off and thus the power source voltage of approx. 12 V in the ECM is applied to the terminal IDL1 of the ECM. The voltage applied to the terminal VTA1 of the ECM increases in proportion to the opening angle of the throttle valve and becomes 3.2 ~ 4.9 V when the throttle valve is fully opened. The ECM judges the vehicle driving conditions from these signals input from terminals VTA1 and IDL1, and uses them as one of the conditions for deciding the air-fuel ratio correction, power increase correction and fuel-cut control etc.