Circuit Description

Exhaust Gas Recirculation (EGR) system controls formation of oxides of nitrogen (NOx) emissions by recirculating exhaust gases into combustion chamber. EGR valve is a stepper motor design. Stepper motor moves a spring loaded plunger that controls flow of exhaust gases into intake manifold. Plunger movement is controlled by PCM. By turning stepper motor in different directions, PCM controls opening of exhaust gas passage to intake manifold. Stepper motor has 4 coil windings that control motor movement.