1999 Subaru Legacy Owner's Manual - Page 263

J Brake system B Two separate circuits Your vehicle has two separate circuit brake systems. Each circuit works diagonally across the vehicle. If one circuit of the brake system should fail, the other half of the system still works. If one circuit fails, the brake pedal will goes down much closer to the floor than usual and you need to press it down much harder. And a much longer distance will be needed to stop the vehicle. B Brake booster The brake booster uses engine manifold vacuum to assist braking force. Do not turn off the engine while driving because that will turn off the brake booster, resulting in poor braking power. The brakes will continue to work even when the brake booster completely stops functioning. If this happens, however, you will have to push the pedal much harder than normal and the braking distance will increase. J Disc brake pad wear warning indicators OM-H0163 The disc brake pad wear warning indicators on the disc brakes give a warning noise when the brake pads are worn. If a squeaking or scraping noise is heard from the disc brakes while braking, immediately have your vehicle checked by your SUBARU dealer. 7-32