The Brake Proportioning Valve which is installed on the firewall restricts hydraulic pressure to the rear wheels during hard braking to avoid rear wheel lockup. It is not usable to accomplish this, therefore, if there is an evidence of malfunction, its pressure should be checked by the dealer service department or a repair shop with correct pressure gauges. Should the valve ever be bad, it can be removed by untwisting the
Brake Lines with a flare nut wrench and then unbolting the valve from the bracket it is mounted on. Once the new valve has been installed then the whole brake system has to be flushed out.