1998 Subaru Forester Owner's Manual - Page 185

Starting and operating 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. B ABS system self-checking 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 started. These are caused by an automatic functional test of the ABS system being carried out and does not indicate any abnormal condition. B ABS warning light HS0156 The ABS warning light comes on when the ignition switch is turned to the "ON" position and goes out after about two seconds. This is an indication that the ABS system is working properly. If the warning light behaves as follows, ABS system may not work properly. D The warning light does not come on when the ignition switch is turned to the "ON" position. D The warning light comes on when the ignition switch is turned to the "ON" position, but it does not go out even when the vehicle speed - CONTINUED - 7-31