Deceleration Control System: Description

Decel throttle control (modulator) system keeps throttle valves open slightly during sudden deceleration to help reduce hydrocarbon and carbon monoxide emissions.

System consists of governor module or speed sensor, ported vacuum switch (some models), solenoid vacuum valve, throttle positioner (modulator) on throttle linkage, electrical wiring and vacuum hoses. See Figure .

Some systems also utilize vacuum switch that notifies module or speed sensor when manifold vacuum is at predetermined level. System is electrically connected to ignition switch and to "TACH" terminal of ignition coil.