Throttle Positioner System

On deceleration, on improper air/fuel mixture results. Operated by intake manifold vacuum and electrically connected to engine speed switch, the throttle positioner servo diaphragm keeps throttle plate slightly open to maintain an adequate air/fuel ratio.

When engine speed is above 1700 RPM on 1979 models, speed switch opens throttle positioner circuit, allowing 3-way solenoid valve to energize and permit vacuum to servo diaphragm. Below 1700 RPM, solenoid is not energized and no vacuum passes to servo diaphragm. If equipped with air conditioning, 3-way solenoid is energized whenever A/C control is on. This establishes a slightly higher engine speed.