Circuit Description

Throttle Position (TP) sensor measures amount of throttle valve opening. TP sensor signal voltage varies from about 0.25 volts at closed throttle to about 4 volts at wide open throttle.

TP signal is used by PCM for fuel control and most PCM controlled outputs. PCM monitors throttle position and compares actual throttle positions from the TP sensor to a predicted TP value calculated from engine speed. If PCM detects a continuous short to ground, DTC P0122 will set.

When DTC sets, PCM illuminates MIL as soon as fault is detected. PCM will substitute a default TP sensor value. Default value is based on MAP and RPM. PCM will store conditions present when DTC was set as freeze frame data in the FAILURE RECORDS data.

PCM will turn MIL off on third consecutive trip cycle during which diagnostic runs and fault is no longer recognized. A history DTC P0122 will clear after 40 consecutive trip cycles during which diagnostic runs and fault is no longer recognized. DTC can be cleared with scan tool, or by disconnecting battery voltage feed to PCM.