Circuit Description

The throttle body assembly contains a throttle position (TP) sensor. The TP sensor is mounted within the throttle body assembly and is not serviceable. The TP sensor is a potentiometer which provides a signal voltage that changes relative to the throttle blade angle. The engine control module (ECM) supplies the TP sensor with a common 5-volt reference circuit, a common low reference circuit, and a signal circuit. The TP sensor signal voltage decreases from more than 4 volts at idle to less than 1 volt at wide open throttle (WOT).

The ECM uses the actual TP sensor signal to calculate the predicted mass airflow (MAF) value. The ECM then compares the actual MAF sensor signal to the predicted MAF value. If the ECM detects that the actual MAF sensor signal and the predicted MAF value differ by more than a predetermined amount, and the short term fuel trim remains steady, then the TP sensor signal is considered invalid and this DTC sets.