2006 Subaru Forester Owner's Manual - Page 211

7-16 Starting and operating Disc brake pad wear warning indicators ABS (Anti-lock Brake System) The ABS system prevents the lock-up of wheels which may occur during sudden braking or braking on slippery road surfaces. This helps prevent the loss of steering control and directional stability caused by wheel lock-up. When the ABS system is operating, you may hear a chattering noise or feel a slight vibration in the brake pedal. This is normal when the ABS operates. 700040 The disc brake pad wear warning indicators on the disc brakes give a warning noise when the brake pads are worn. If a squeaking or scraping noise is heard from the disc brakes while braking, immediately have your vehicle checked by your SUBARU dealer. The ABS system will not operate when the vehicle speed is below approximately 6 mph (10 km/h). The ABS system does not always decrease stopping distance. You should always maintain a safe following distance from other vehicles. When driving on badly surfaced roads, gravel roads, icy roads, or over deep newly fallen snow, stopping distances may be longer for a vehicle with the ABS system than one without. When driving under these conditions, therefore, reduce your speed and leave ample distance from other vehicles. When you feel the ABS system operating, you should maintain constant brake pedal pressure. Do not pump the brake pedal since doing so may defeat the operation of the ABS system. Always use the utmost care in driving - overconfidence because you are driving with an ABS equipped vehicle could easily lead to a serious accident. ABS system self-check You may feel a slight shock in the brake pedal and hear the operating sound of ABS from the engine compartment just after the vehicle is started. This is caused by an automatic functional test of the ABS system being carried out and does not indicate any abnormal condition.