Hydraulic System Control Valves: Description

All vehicles have some type of hydraulic system control valve or switch in the brake system. Unit is usually mounted on left front fender splash shield or frame side rail beneath master cylinder, and is connected to master cylinder and wheel cylinders through hydraulic lines. Drum brake vehicles use a simple pressure differential warning switch. Disc brake vehicles (except Corvette) use valves which combine the warning switch with a metering valve, a proportioning valve, or both.