Expedition 2WD V8-4.6L SOHC VIN 6 (1999)
Brake Proportioning/Combination Valve: Description and Operation
Brake Master Cylinder Fluid Control Valve
The brake master cylinder fluid control valve regulates the hydraulic pressure in the rear brake system. It is located on the brake master cylinder and is
screwed into the rearmost outlet port. When the brake pedal is applied, the full brake pressure passes through the brake master cylinder fluid control
valve to the rear brake system until the valve's split point is reached. Above its split point, the brake master cylinder fluid control valve begins to
reduce the hydraulic pressure to the rear brakes, creating a balanced braking condition between the front and rear wheels to minimize rear wheel
lockup during hard braking.
In the case of front brake system malfunction, the brake master cylinder fluid control valve has a bypass feature which allows full hydraulic pressure to
the rear brake system.
