Description & Operation
WARNING: This page is about a different car, the 2002 Toyota Prius, 2002 Toyota Land Cruiser, 2002 Toyota 4Runner, 2001 Toyota Prius, and 2001 Toyota 4Runner. However, it is still accessible from the selected car via links, so may be relevant.
Hydraulic Brake Booster (HBB) System consists of brake fluid reservoir, pressure accumulator, hydraulic pump motor, brake master cylinder and associated electrical components. System is connected to Anti-Lock Brake (ABS) system ECU to allow for ease of fault diagnosis and isolation.
Operation of brake pedal applies hydraulic pressure to front brakes assisted by brake booster and accumulator pressure. Rear brakes receive hydraulic pressure from accumulator directly. In the event of HBB pump motor failure, brake pressure to rear wheels will be lost. Brake system warning buzzer sounds in event of system pressure failure, or excessive pump motor operation.