Exhaust Gas Recirculation (EGR) Cooler System
The exhaust gases are directed through the EGR cooler to lower the exhaust gas temperature before entering the intake manifold. Coolant from the secondary cooling system reduces the exhaust gas temperature when the gases are directed through the EGR cooler by closing the EGR bypass valve.
The PCM controls the EGR cooler bypass valve by commanding the EGR cooler bypass solenoid duty cycle. When the EGR cooler bypass valve is commanded closed, 0% duty cycle, the exhaust gases pass through the EGR cooler to the intake manifold. When the EGR cooler bypass valve is commanded open, 100% duty cycle, the exhaust gases pass directly to the intake manifold without passing through the EGR cooler.
For additional information on the EGR cooler system components, refer to ENGINE CONTROL COMPONENTS in this article.