2004 Lexus LS 430 User Guide 2 - Page 377

STARTING AND DRIVING 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 86 or 358. TIRE PRESSURE WARNING SYSTEM The tire pressure warning system is designed to provide warning using a message in the multi-information display, master warning light and warning tone when tire inflation pressure is critically low while driving. This message appears to inform you that such low tire pressure may hamper driving. As this system is not designed to operate when the vehicle is stopped, check the tire inflation pressure regularly. The recommended cold tire inflation pressure, tire size and the vehicle capacity weight are on the tire and loading information label. (For instructions, see "Checking tire inflation pressure" on page 464.) Installed tires should be of the specified size. They should be of the same size and construction. If tires other than the specified size are used, or if tires of different sizes or constructions are mixed, the tire pressure warning system will not function properly. 359