Throttle Position Sensor (TPS)

The TP sensor is a potentiometer that is mounted on throttle body and provides PCM with information on throttle valve angle. The PCM provides a 5 volt reference signal and a ground to TP sensor and sensor returns a signal voltage that changes with throttle valve angle. At closed throttle (close to zero degrees) TP sensor output signal is low (below 1 volt) and at WOT (approximately 85 degrees) TP sensor output signal is high (approximately 5 volts). Because TP sensor is not adjustable, PCM must account for build tolerances that could affect TP sensor output at closed throttle. The PCM uses a reaming algorithm so that it can correct for variations of up to six degrees of throttle angle. See Figure and Figure .

The PCM uses TP information to modify fuel control based on throttle valve angle. For example, power enrichment occurs when throttle angle approaches WOT. Acceleration enrichment occurs when throttle angle increases rapidly (similar to an accelerator pump on a carburetor). A faulty TP sensor may cause various driveability conditions and should set a PCM Trouble Code.