Circuit Description

The PCM controls engine speed by adjusting the position of the throttle control valve (DC motor). The throttle motor is a DC motor driven by one coil. The PCM applies current to the DC motor coil in PWM (percent) to adjust the throttle valve into a passage in the throttle body to allow air flow. This method allows highly accurate control of engine speed and quick response to changes in engine load. The Accelerator Position (AP1) sensor circuit provides a voltage signal relative to accelerator pedal angle. The accelerator pedal angle will vary about 13 percent at idle position to about 87 percent at Wide Open Throttle (WOT). APS signal is used to determine which DC motor will adjust throttle position. After the APS signal has been processed by the PCM, it will command DC motor to allow movement of throttle position.