What is a throttle position sensor?

Throttle Position Sensor (TPS) is basically a rheostat. Here is how Merriam Webster defines it: ; Main Entry: : rheo·stat ; Pronunciation: : \ˈrē-ə-ˌstat\ ; Function: : noun ; Date: : 1843 : a resistor for regulating a current by means of variable resistances

Basically, the TPS offers variable resistance depending on the winding or unwinding of its actuator. When you goose the throttle, or take your foot off the gas, the TPS tells your vehicle's computer where the throttle is. Look under your hood at your fuel rail or throttle body. on one side you will see the terminus of the throttle cable and the cam around which the cable is wound. Directly on the opposite side of the throttle body from here, you will see the TPS.