2002 Toyota Prius Owners Manual - Page 162

HYDRAULIC BRAKE 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. The brake system warning light may stay on for about 60 seconds after the ignition key is turned to the "ON" position. It is normal if the light turns off after a while. Depressing the brake pedal repeatedly may turn on the brake system warning light and buzzer. It is normal if the light turns off and the buzzer stops sounding after a few seconds. You may hear a small sound in the engine compartment after the hybrid system 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. ANTI-LOCK BRAKE SYSTEM The anti-lock brake system is designed to automatically help prevent lock-up of the wheels during a sudden braking or braking on slippery road surfaces. This assists in providing directional stability and steering performance of the vehicle under these circumstances. Effective way to press the ABS brake pedal: When the anti-lock brake system function is in action, you may feel the brake pedal pulsating and hear a noise. In this situation, to let the anti-lock brake system work for you, just hold the brake pedal down more firmly. Do not pump the brake in a panic stop. This will result in reduced braking performance. The anti-lock brake system becomes operative after the vehicle has accelerated to a speed in excess of approximately 10 km/h (6 mph). It stops operating when the vehicle decelerates to a speed below approximately 5 km/h (3 mph). 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 Toyota dealer. CAUTION D Do not pump the brake pedal if the hybrid system is not operating. Each push on the pedal uses up your reserved brake fluid pressure. D Even if the power assist is completely lost, the brakes will still work. But you will have to push the pedal hard, much harder than normal. And your braking distance will be longer. 153