Throttle position sensor is also called throttle opening sensor or throttle switch. Its main function is to detect whether the engine is in an idling condition or a load condition, whether it is an acceleration condition or a deceleration condition. It is essentially a variable resistor and several switches, installed on the throttle body, and its appearance and internal structure are shown in the figure below.
The shaft of the resistor is linked with the throttle, and it has two contacts: a fully open contact and an idle contact. When the throttle is in the idle position, the idle contact is closed, and the idle speed signal is output to the computer; when the throttle is in other positions, the idle contact is opened to output voltage signals at different rotation angles relative to the throttle, and the computer will follow the signal The voltage value identifies the load of the engine; according to the increase or decrease rate of the signal voltage within a certain period of time, it is recognized whether it is an acceleration or deceleration condition. The computer corrects the fuel injection volume or performs fuel cut-off control based on the information of these operating conditions.