Throttle Position Sensor: Description and Operation

The Throttle Position (TP) sensor is mounted to the throttle body and connected to the throttle plate shaft. The throttle position sensor is a potentiometer with a five volt reference input and a signal ground supplied by the PCM. A sensor output signal to the PCM is a DC signal that varies according to throttle position angle. As the throttle angle changes the signal to the PCM varies.

The throttle position sensor is used in conjunction with other engine sensors to relay input to the PCM in order to control a 14.7 to 1 air/fuel ratio under all throttle positions.

At a closed throttle position, the output of the throttle position sensor is low (approximately 0.5 volt). As the throttle plate opens, the output signal increases so that, at wide-open throttle, the output voltage will be high (approximately five volts).

An unstable throttle position sensor at idle, varying more than four counts will disrupt closed loop engine idle control.