Document QdgJZmVjxDQj7OXrKgMxvyvk

Warning Lights and Valves & BRAKE SYSTEM \ 'i * Introduced in 1967, and required by federal law since When vehicles are equipped with disc brakes, there 1968, a warning light switch is used with the dual may be two additional valves in the system. One is master cylinder. The switch is designed to light a called a proportioning valve, which reduces pressure brake warning light on the dash panel if a' failure to the rear drum brakes during braking. Since disc occurs in either the front or rear hydraulic system. brakes require a higher hydraulic line pressure, it is This light may also indicate that the parking brake is necessary to have a proportioning valve to maintain applied. It is wired into the started circuit to advise the correct balance between the line pressures to the the driver of a brake warning light failure. The front and rear brakes. warning light switch consists of a normally centered On some vehicles a metering valve is also used. This shuttle. Upon failure in either half of the system, a valve acts to delay pressure buildup to the front disc brake application results in greater pressure on one brakes on application. Its purpose is to reduce front end of the shuttle, forcing it to shift, making a brake pressure until rear brake pressure overcomes contact completing the electrical circuit. the shoe return springs. In this way, a balanced brake system is achieved.