Proportioning Valves
NOTE:
Only vehicles without anti-lock brakes have proportioning valves. Vehicles with anti-lock brakes have Electronic Variable Brake Proportioning (EVBP) that is built into the Integrated Control Unit (ICU).
Proportioning valves balance front to rear braking by controlling the brake fluid hydraulic pressure to the rear brakes. Under light pedal application, the proportioning valve allows normal fluid flow to the rear brakes. Under higher pedal effort, the valve reduces fluid pressure to the rear brakes.
The non-anti-lock brake master cylinder is a 4 outlet design with 2 screw-in proportioning valves attached directly to the master cylinder housing. One proportioning valve controls each rear brake.