Throttle Position Sensor: Description and Operation

Throttle Position (TP) Sensor
The TP sensor detects the throttle valve opening. The TP sensor contains a potentiometer and a contact switch. The contact switch is known as the Closed Throttle Position (CTP) switch. The potentiometer is connected to the throttle valve shaft on the throttle body and is responsible for sending the throttle position signal to the Powertrain Control Module (PCM).

A 5 volt reference voltage is applied to the TP sensor from the PCM. The voltage reading at the PCM changes as the throttle plate opening increases. The PCM can calculate the throttle valve opening by monitoring the TP sensor output voltage.

The PCM uses the TP sensor signal for one of the inputs in order to control the fuel injector, the idle speed control motor and the exhaust gas recirculation solenoid vacuum valve. The PCM also converts the TP sensor voltage input into an ON/OFF signal for use by the automatic transmission.