Throttle Position Sensor: Description and Operation

Throttle Body Exploded View:

DESCRIPTION
The Throttle Position (TP) sensor is a potentiometer that is mounted on the throttle body and provides the PCM with information on throttle valve angle. The PCM provides a 5 volt reference signal and a ground to the TP sensor and the sensor returns a signal voltage that changes with throttle valve angle. At closed throttle (close to O degrees) the TP sensor output signal is low (below 1 volt) and at WOT (greater than 8O degrees) the TP sensor output signal is high (above 4 volts).

PCM INPUT
The PCM uses TP information to modify fuel control based on throttle valve angle. For example, power enrichment occurs when the throttle angle approaches WOT. Acceleration enrichment occurs when the throttle angle increases rapidly (similar to an accelerator pump on a carburetor).

PCM CORRECTIONS
Because the TP sensor is not adjustable, the PCM must account for build tolerances that could affect the TP sensor output at closed throttle. The PCM uses a learning process so that it can correct for variations of up to 6 degrees of throttle angle.

FAULTY TP SENSOR
A faulty TP sensor may cause various driveability conditions and should set a Diagnostic Trouble Code.