Abstract: An automatic control circuit for a brake control device, relays around the device, light lamps and other parts to be operated differently under different circumstances, e.g., braking while running, braking to stop, releasing the brake pedal after braking, starting, parking after braking, and operation when the car stops in semi-automatic. The automatic control circuit operates a valve in the hydraulic system which isolates the system after hydraulic pressure is increased, thus maintaining braking pressure even when the brake pedal is released. The valve isolates the hydraulic system until the clutch pedal is released and the accelerator pedal is depressed, then the valve is allowed to open and pressure is released. A vehicle movement detector is coupled to the circuit which ensures that brake pressure will not automatically be maintained when the vehicle is moving.