Throttle Position Sensor: Description and Operation

Throttle Position Sensor:

LOCATION

The Throttle Position Sensor (TPS) is located on the top of the fuel injection pump.

PURPOSE

This sensor, found on automatic transmission applications only, is used to send input signals to the engine controller to indicate the current angle of the throttle blade.


THEORY/OPERATION

This sensor is a variable resistor that has a 5 volt reference signal applied to it by the electronic controller. The Throttle Position Sensor (TPS) sends signals back to the electronic controller in the range of approximately 1 to 4 volts, depending upon the throttle shaft angle. The electronic controller uses these input voltages to determine the current position of the throttle.

An input voltage of approximately 1 volt indicates a minimum throttle opening or idle condition. An input voltage of approximately 3.5 volts would indicate a maximum throttle opening or wide open throttle condition.

The Throttle Position Sensor's (TPS) input is used to determine when the 3-4 upshift or the 4-3 downshift (automatic transmission with overdrive) should occur.