Throttle Position Sensor: Description and Operation

The Throttle Position Sensor (TPS) is a variable resistor that is mounted in the carburetor float bowl. The TPS plunger is under the pump lever. As the TPS varies position, so does the signal to the ECM. The ECM measures the voltage output of the TPS. At closed throttle the voltage is about 1 volt or less and as the throttle opening is increased, the voltage is increased to about 5 volts at wide-open throttle. The ECM uses the TPS information to regulate the M/C solenoid, idle speed, EST and TCC.