How does auto cruise control work?

Answer 1

Cruise control uses an actuator to open the throttle of your vehicle.

The amount it opens the throttle is controlled by the computer ECU or a module on older models. The ECU gets its input from the vehicle speed sensor or a hall effect type sensor attached to the drive shaft on older models.

As already mentioned it will not engage at lower speeds and will disengage if the brake or clutch is applied.

Answer 2

The cruise control system actually has a lot of functions other than controlling the speed of your car. For instance, the cruise control can accelerate or decelerate the car by 1 mph with the tap of a button. Hit the button five times to go 5 mph faster. There are also several important safety features -- the cruise control will disengage as soon as you hit the brake pedal, and it won't engage at speeds less than 25 mph (40 kph).

Answer 3

you select the speed you want , the cruise unit has a spedometer cable input so it tries to maintain that speed by changing the throttle position according to engine load ( up or down hills ) engine load is reflected in the amount of intake manifold vacuum, more vac. less load ( downhill ) increased speedo. input, reduced throttle opening, speed is maintained . uphill the opposite , lowered engine vac. , throttle opened more ( which in itself lowers vac. ) to maintain the programed speed .(these things were on cars long before the computer was )