Brake Proportioning/Combination Valve: Description and Operation

The brake pressure control valve:
- regulates the hydraulic pressure in the rear brake system.
- is a fixed-type located at the body side member under the brake booster on station wagons with or without anti-lock brakes. Valve is different based on whether or not system has anti-lock brakes.
- is a height sensing variable-type located between the body and LH rear suspension quadra-link on the sedan with or without anti-lock brakes. Valve is the same on all sedans.

A junction block is located on the body side-member under the brake booster on sedans without anti-lock brakes.
Operation is as follows:
- When brake pedal is applied, the rear brake fluid pressure passes through the control valve to the rear brake system until the valve's pre-determined maximum pressure point is reached.
- The control valve maintains the pre-determined maximum hydraulic pressure to the rear brakes, creating a balanced braking condition between the front and rear wheels to minimize rear wheel skidding during hard braking.
- The height sensing feature of the sedan's brake load sensor proportioning valve increases the maximum pressure to the rear brakes as the lever is moved toward the valve.