Subaru LEGACY 2002 Quick Reference Index page 416

VEHICLE DYNAMICS CONTROL (VDC) SYSTEM
VDC
6. PRESSURE "HOLD" CONTROL WITH BRAKE PEDAL NOT DEPRESSED
The cut solenoid valve, suction solenoid valve and inlet solenoid valve are all energized, while the
outlet solenoid valve is de-energized. This means that the ports of the cut solenoid valve, inlet so-
lenoid valve and outlet solenoid valve are closed, while the port of the suction solenoid valve is
open.
In this state, the pump is activated, forcing the brake fluid in the master cylinder reservoir tank
through the open port of the suction solenoid valve. The fluid passage is, however, blocked by the
closed inlet solenoid valve. Since the port of the outlet solenoid valve is also closed, the fluid pres-
sure in the wheel cylinder is held unreleased.
The fluid pressure generated by the pump becomes higher and higher because the port of the inlet
solenoid valve is closed. When it reaches a certain level, the built-in relief valve of the cut solenoid
valve opens and allows the brake fluid to return into the master cylinder reservoir tank.
NOTE:
For simplicity of explanation, operation of the hydraulic control unit is represented by operation of
a single wheel circuit.
VDC-18