Subaru 2002 Impreza Service Manual page 318

ANTI-LOCK BRAKE SYSTEM (ABS)
ABS
2. PRESSURE "DECREASE" CONTROL (ABS ACTIVE)
Both the inlet and outlet solenoid valves are energized, which means that the inlet port is closed
and the outlet port is open.
In this state, the wheel cylinder is isolated from the master cylinder but open to the reservoir, so
the brake fluid in it can be drained into the reservoir, decreasing its pressure and reducing the
braking force of the wheel.
The brake fluid collected in the reservoir is forced into the master cylinder by the pump.
During this phase of ABS operation, the pump motor continues operating.
NOTE:
For simplicity of explanation, operation of the hydraulic control unit is represented by operation
of a single wheel circuit.
ABS-1 2