Circuit Description

Throttle Position (TP) sensor is mounted on throttle body and detects throttle opening angle. When throttle valve is fully closed, at engine idle, about 0.3-0.8 volt is applied to TP input circuit. Voltage will increase in proportion to amount of throttle valve opening angle. At Wide Open Throttle (WOT), TP input circuit voltage is about 3.2-4.9 volts. PCM determines vehicle driving condition from TP sensor input and calculates air-fuel ratio correction, power increase correction and fuel-cut control. DTC P0121 will set when vehicle speed exceeds 19 MPH, and TP sensor output value is out of applicable range.

When DTC sets, MIL will illuminate after 2 consecutive ignition cycles in which diagnostic runs with active fault. PCM will record operating conditions at time of diagnostic failure and store information in freeze frame buffer.