If the car is maintaining it's speed without your foot on the gas the cruise control is on... The human brain is way better than an LED. If you need to look at a light to tell you the cruise control is on, you need to have your drivers license taken away from you. Tap the break, if I'm not mistaken all cruise control systems are legally required to completely turn off in the event the break pedal is pushed to the point where any breaking would actually occur.