Abstract: A system for selectively controlling the flow of brake fluid to the brakes of a two or four wheel drive vehicle utilizes a separate solenoid valve on each brake fluid line leading directly to a driven wheel. The valves are normally open, and are operated by primary and secondary electrical switches arranged in series. The primary electrical switch must be physically depressed and held to be activated and the secondary switch which is separately connectible to each solenoid valve, is actuated by the primary switch in such a manner as to separately activate each solenoid valve to control the flow of brake fluid to the brake of each drive wheel.