2005 Lexus RX 330 Owners Manual - Page 492

STARTING AND DRIVING Drum−in−disc type parking brake system Your vehicle has a drum−in−disc type parking brake system. This type of brake system needs bedding−down of the brake shoes periodically or whenever the parking brake shoes and/or drums are replaced. Have your Lexus dealer perform the bedding−down. Brake assist system If you slam the brakes on such as in an emergency or apply the brakes more firmly than usual such as when descending the hill with the designated number of occupants in the vehicle, the brake assist system provides more powerful braking. If you slam the brakes on or apply the brakes more firmly, more powerful braking will be applied. At this time, you may hear a sound in the engine compartment and feel the vibrations of the brake pedal. This does not indicate a malfunction. The brake assist 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). For an explanation of this system's warning light, see "ABS warning light" on page 81 or 460. 461