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Cruise Control Systems: Operation: Notes

System operation is controlled by electronic controller module. The ECM monitors the vehicle speed through the speed sensor. It also monitors operation of the multi-function control switch, located on end of turn signal lever and servo position. As commands as relieved from the multi-function control switch, the electronic control module either holds the current position of the servo. Applies vacuum to the servo to increase throttle position (accelerates). Or vents vacuum from the servo to reduce vehicle speed (deceleration). System can be disengaged by turning off cruise control switch or by activating brake or clutch (M/T) release switches. A vacuum release valve controls servo vacuum release to the atmosphere as either pedal is depressed. This allows servo to quickly release throttle linkage, returning throttle to idle position.

Fig 1: Multi-Function Control Switch
G16063Courtesy of GENERAL MOTORS CORP.