Throttle Position Sensor: Description and Operation

Throttle Position Sensor (TPS) Operation:

The Throttle Position Sensor (TPS) is a potentiometer that is mounted to the throttle body.

The TPS is a three wire sensor with a referance voltage, a ground provided by the ECM, and a sensor output signal to the ECM. The sensor output signal is a DC voltage that varies with throttle angle.

The ECM supplies a five-volt signal to the sensor through a resistor in the ECM and measures the signal voltage. As the throttle angle is changed (accelerator pedal moved), the output of the sensor also changes. At closed throttle, the out put voltage is low. As throttle angle increases, the output increases so that, at wide open throttle, the output approaches 5 volts.

By monitoring the output voltage of the TPS, the ECM can modify fuel delivery based on throttle angle.

The TPS also houses an idle switch. The ECM supplies both ignition voltage and a ground to the idle switch. When the throttle is closed, the ECM senses the voltage drop caused by the switch closed to ground. The ECM uses this information as a reference for idle air control operation.

A failure in the TPS sensor circuit should set a Diagnostic Trouble Code (DTC) 41.