Throttle Position Sensor: Description and Operation

Throttle Position Sensor (TPS):

PURPOSE
The Throttle Position (TP) Sensor is a non-adjustable potentiometer that senses throttle angle and relays the information to the control module. This input to the control module is used to control the fuel system and most of the control module outputs.

CONSTRUCTION
The TP sensor has internally three circuits. One to ground, the other from the control module as a 5.0 volt reference source and a third circuit is used by the control module to measure the output voltage . The TP sensor voltage output varies from about .5 volt at idle to about 4.9 volts at wide open throttle (WOT).

OPERATION
As the throttle valve rotates in response to movement of the accelerator pedal, the throttle shaft transfers this rotation movement to the TP sensor. A potentiometer (variable resistor) within the Throttle Position (TP) sensor assembly changes its resistance in proportion to throttle movement.
If the TP sensor senses a Wide Open Throttle proportion to throttle movement. (WOT), a voltage signal indicating this condition is sent to the control module. The control module then increases the injector base pulse width, permitting increased fuel flow.
By applying a reference voltage (5.0 volts) to the TP signal input, a varying voltage (reflecting throttle position) is available at the TP output. For example, approximately 2.5 volts results from a 50% throttle valve opening (depending on TP calibration). The voltage output from the TP assembly is routed to the control module for use in determining throttle position.

LOCATION
The non-adjustable Throttle Position (TP) sensor, is mounted on the side of the throttle body opposite the throttle lever assembly.