Circuit Operation

The cruise control system operates a mechanical likage to the throttle by means of a vacuum motor. This is a diaphragm moved by a vacuum motor applied to one side. A solenoid operated valve connects the vacuum motor to a vacuum tank. Another solenoid valve vents the vacuum to reduce suction. The instrument panel controls the vacuum motor and the throttle byu pulsing these solenoid valves on and off.

One input to the instrument panel is the vehicle speed. This input comes from the Vehicle Speed Sensor. If the actual speed signal is different from the speed that was set into and remembered by the Instrument Panel, the Instrument Panel generates pulses to change the vacuum adn return the vehicle to the set speed. The veicle Speed Sensor is mounted on the transmission. Other inputs to the Instrument Panel are from the Cruise Switch adn the Set Switch. A disengaged input to the Instrument Panel comes from a switch on the brake pedal. In cars with a manual transmission, a switch on the clutch pedal will also disengage the Cruise Control.

The two outputs of the Instrument Panel operates the coils of the vacuum valve and the vent valve. Both valves are located in the Cruise Control Servo. These valves move the throttle by means of the vacuum motor. Ther Servo Position Sensor coil senses the position and motion of the vacuum motor. It feeds this information back to the Instrument Panel to provide smooth acceleration while the vehicle is in Cruise Control.