Vehicle Speed Control

VEHICLE SPEED CONTROL (NGC I)
The PCM controls vehicle speed by operation of the speed control servo vacuum and vent solenoids. Energizing the vacuum solenoid applies vacuum to the servo to increase throttle position. Operation of the vent solenoid slowly releases the vacuum allowing throttle position to decrease. A special dump solenoid allows immediate release of throttle position caused by braking, cruise control turn off, shifting into neutral, excessive RPM (tires spinning) or ignition key off.


VEHICLE SPEED CONTROL (NGC II)
The PCM controls vehicle speed by controlling the throttle opening to achieve the selected vehicle speed under all driving conditions. Cruise control switches used on NGC II vehicles have two inputs per switch. No servo or solenoids are used with this system.