Cruise Control: Description and Operation

Fig. 1 Cruise control transducer with resume feature:

This system is used on all 1982---83 models, except Cadillac, DeVille, Eldorado, Fleetwood Brougham and Seville models. The system includes a transducer type regulator, Fig. 1, a vacuum operated actuator that controls throttle position, control switches mounted on the turn signal lever and cut-off switches activated by the brake and clutch pedals.
The transducer is driven by the speedometer cable and converts the rotation of the cable into an electrical value that is proportional to vehicle speed. The servo unit maintains the selected road speed and is operated by vacuum which is regulated by the transducer. The system is initially energized when the control switch (ON/OFF/RESUME) is moved to the ON position. When the engage button on the end of the turn signal switch is depressed half-way, then released, the transducer locks onto the present speed value and controls vacuum applied to the servo in order to maintain that value. However, a low speed switch within the transducer prevents the system from engaging at speeds below 25---40 mph.
The transducer maintains the selected speed until the system is deactivated, either by moving the control switch to the OFF position or by depressing the brake or clutch pedal. When the system is deactivated by depressing the brake or clutch pedal the transducer holding solenoid is deenergized and a vacuum switch vents servo vacuum to atmosphere. However, the speed value set in the transducer with the engagement switch is retained, and moving the control switch to RESUME will cause the transducer and resume solenoid to return the vehicle to the previously selected speed. When the system is deactivated by moving the control switch to the OFF position or by turning off the ignition, the speed value set by the engage switch is lost and the system must be reset.