1974-76 Models

When coolant temperature is below 113°F(45°C), coolant thermal switch is closed allowing EGR solenoid valve to be energized. When solenoid is energized, it does not permit vacuum to reach EGR valve and allows pressure from air pump to act upon valve. This causes the EGR valve to close and no exhaust gas recirculation will take place.

As engine warms up, thermal switch opens and de-energizes solenoid valve. This will allow exhaust gas recirculation to take place if throttle is between idle and wide open throttle position.