Just remember, when the ABS light comes on, your brakes are NOT affected.
However, when the ABS light is on, that means your ABS system is "Offline". That means you are back to conventional brakes without the computer's assistance in braking under less than ideal conditions.
If your ABS light remains on after engine start, that means that the ABS system failed its self-test. The most common reason for this is either an open circuit to one of the sensors (or the sensor) or an open circuit in one of the pump's valve solenoids. The only way to find out exactly where to focus diagnostic efforts is to extract the ABS failure codes.
Steve
