Throttle Position Sensor (TPS)
The TPS is mounted on side of the throttle body and is connected to the throttle shaft. As throttle valve angle changes, the resistance of the sensor also changes. The ECM supplies a 5-volt reference signal to the TPS. A closed throttle condition produces high resistance at the sensor and the output signal to the ECM will be low (about .5 volts). A wide open throttle condition produces low resistance at the sensor. The output signal to the ECM will be high (about 5 volts).
By monitoring the output voltage of the TPS and comparing that value to the reference signal, the ECM can calculate fuel requirements based upon throttle valve angle (driver demand).
NOTE:
For information on other sensors that are used by the ECM to control engine performance and other systems, refer to GENERAL MOTORS COMPUTER COMMAND CONTROL article in COMPUTERIZED ENGINE CONTROLS section.