Throttle Position Sensor: Description and Operation

Throttle Position Sensor:

The Throttle Position Sensor (TPS) is connected to the throttle valve shaft in the throttle body unit. The TPS is a potentiometer with one connection to ground, and the other to the computer 5.0 volt reference source. A third wire from the computer is used to measure the output voltage from the TPS. As the throttle angle changes (pressing down on accelerator pedal) so does the TPS voltage output. By monitoring TPS voltage output, the computer can determine fuel delivery rate based on throttle valve angle or driver demand. The ECM has the ability to auto-zero the TPS voltage if it is below 1.25 volts. This means that any voltage less than 1.25 volts, the ECM will adjust to 0% throttle opening.