C 1500 Truck 2WD V8-454 7.4L (1990)
EGR Control Solenoid: Description and Operation
EGR Vacuum Solenoid (Under 8500 Gvw)
The ECM will energize the EGR solenoid (EGR "ON") when the engine is warm and above idle. There is little EGR flow at wide open throttle due to
lack of vacuum.
