2004 Lexus RX 330 Owners Manual - Page 531

STARTING AND DRIVING BRAKE SYSTEM The tandem master cylinder brake system is a hydraulic system with two separate sub-systems. If either sub-system should fail, the other will still work. However, the pedal will be harder to press, and your stopping distance will increase. Also, the brake system warning light may come on. Brake booster The brake booster uses engine vacuum to power-assist the brakes. If the engine should quit while you are driving, you can bring the vehicle to a stop with normal pedal pressure. There is enough reserved vacuum for one or two stops but no more! CAUTION CAUTION Do not drive your vehicle with only a single brake system. Have your brakes fixed immediately. D Do not pump the brake pedal if the engine stalls. Each push on the pedal uses up your reserved vacuum. 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 increase. 508