Circuit Description

PCM controls engine speed by adjusting position of throttle control valve. Throttle control valve motor is a DC motor driven by one coil. PCM applies voltage to DC motor in steps (percentages) adjusting air flow through the throttle body. This method allows accurate control of engine speed and quick response to changes in engine load.

Accelerator Position Sensor (APS) circuit provides a voltage signal relative to accelerator pedal angle. APS1 angle varies from 13 percent at idle to 87 percent at wide open throttle. APS signal is used to determine throttle valve adjustment position. APS signal is processed by PCM, PCM then commands throttle valve motor to move throttle valve.