The dual circuit brake control valve provides two functions. It distributes pressurized brake fluid from the master cylinder to the diagonal brake circuits (left front/right rear and right front/left rear), and also reduces the pressure of the fluid supplied to the rear brakes in the event of hard braking, preventing the wheels from blocking.
The control valve is beyond repair. It rarely breaks, so before replacing this valve, first fully check all other possible causes of brake failure.
The valve is located either on the right wing or directly below the master cylinder. Before removing the valve, mark the positions of each brake line on the valve. Carefully remove the pipes from the valve and plug them immediately. Unscrew the valve from the mount. When assembling, fix the valve securely. Hand-tighten each piping to the respective valve ports, then tighten the connections to 15 Nm with a ring wrench. Do not drag connections.