Cruise Control Vacuum System

The cruise control system uses vacuum to operate a servo unit that adjusts throttle position to maintain a desired vehicle speed. The electronic control module of the cruise control system operates a vacuum valve and a vent valve in the servo to trap enough vacuum in the servo to hold the required throttle setting. A vacuum release valve on the brake pedal bracket vents the trapped vacuum to atmosphere when the brake pedal is depressed, allowing the servo to quickly return the throttle to idle.