The antilock brake system (ABS) helps prevent a vehicle’s wheels from locking during “panic” braking, which allows the driver to maintain greater steering control as the vehicle is quickly slowed—a key factor in avoiding a collision.

However, ABS does not guarantee you will avoid a crash. In fact, you still may lose control when driving at excessive speed or during extreme steering maneuvers.

All passenger cars equipped with ABS have four-wheel ABS. SUVs, trucks, and vans equipped with ABS may have either four-wheel or two-wheel ABS. Four-wheel ABS monitors and controls all the wheels of the vehicle, whereas two-wheel ABS only monitors and controls the rear wheels. In vehicles with two-wheel ABS, the front wheels can still lock during hard or panic braking and this lockup can result in the loss of steering control.

Some four-wheel ABS systems include Brake Assist, which is only available with ABS systems. During emergency braking, this feature provides more brake power to help the driver achieve full brake-pedal force. Under certain conditions, Brake Assist can potentially reduce overall stopping distance by activating the braking system more quickly.

Source: National Highway Traffic Safety Administration (NHTSA) and www.safercar.gov