The brake switch is an important input. The car will not Ready without it. Like the Power Switch, the brake switch contains two separate switches for error checking. The brake switch for the Smart Key system is the same as the brake switch for the brake lights, so if the brake lights work, the brake switch signal is being recognized. On the Camry HV, the Power Button LED will illuminate when the brake pedal is pressed, allowing for a in-car brake switch check.