2004 Lexus GX 470 Owners Manual - Page 457

STARTING AND DRIVING Brake assist system When you slam the brakes on, the brake assist system judges as an emergency stop and provides more powerful braking for a driver who cannot hold down the brake pedal firmly. When you slam the brakes on, 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). The brake assist system may not work for about 60 seconds after the engine is started. For an explanation of this system's warning light, see "ABS warning light" on page 67. TIRE PRESSURE WARNING SYSTEM The tire pressure warning system is designed to provide warning when tire inflation pressure of one or more of your tires (including the spare tire) is low. The low tire pressure warning light comes on to inform you that low tire inflation pressure may hamper 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. " Low tire pressure warning light This light comes on when the ignition key is turned to the "ON" position. It goes off after a few seconds. This indicates that the tire pressure warning system is functioning properly. 434