Throttle Position Sensor: Description and Operation

THROTTLE POSITION (TP) SENSOR
The Throttle Position (TP) sensor mounts on the side of the throttle body and is connected to the throttle blade shaft.

The TP sensor is a variable resistor (potentiometer) whose resistance changes according to throttle blade shaft position. During acceleration, the TP sensor resistance decreases; during deceleration, the TP sensor resistance increases.

The Engine Control Module (ECM) applies a reference voltage to the TP sensor and then measures the voltage that is present on the TP sensor signal circuit. The ECM uses the TP sensor signal to adjust timing and injector pulse width. The TP sensor signal along with the MAF sensor signal is used by the ECM to calculate engine load.

The TP Sensor is a rotating type variable resistor that rotates with the throttle shaft to sensor the throttle valve angle. As the throttle shaft rotates, the throttle angle of the TP Sensor changes and the ECM detects the throttle valve opening based on the change of the throttle angle.