2000 Lexus GS 300 Owners Manual - Page 336

STARTING AND DRIVING BRAKE SYSTEM This brake system has 2 independent hydraulic circuits. If either circuit should fail, the other will still work. However, the pedal will be harder to press, and your stopping distance will be longer. Also, the brake system warning light may come on. CAUTION Do not drive your vehicle with only a single brake system. Have your brakes fixed immediately. Brake booster The brake booster uses brake fluid pressurized by the pump to power-assist the brakes. If the brake booster fails during driving, the brake system warning light comes on and buzzer sounds continuously. In this case, the brakes may not work properly. If they do not work well, depress the brake pedal firmly. If the brake system warning light comes on, immediately stop your vehicle and contact your Lexus dealer. The brake system warning light may come on for about 60 seconds after the engine is started. It is normal if the light goes out after a while. Depressing the brake pedal repeatedly may turn on the brake system warning light and buzzer. It is normal if the light goes out and the buzzer stops sounding after a few seconds. 316 You may hear a small sound in the engine compartment after the engine is started or the brake pedal is depressed repeatedly. This is a pump pulsating sound of the brake system, and it is not a malfunction.