Why is the anti lock brake light on? Well if the abs light came on it means that there is a fault somewhere in the anti-lock brake system. But if the ABS light came on for a couple of seconds when the engine is started then this is normal, it indicates of the self-test of the system.
Anti lock brake system is very complicated since it involves several sensors and computers to regulate and monitor the system. If the ABS light came on while driving then there is fault with the system, however it doesn’t mean that car will have no brake when the light came on.
If there is fault with system the standard brake will still work fine , the only problem is during panic braking when the driver step on the brake pedal really hard the brake will lock up and the driver will not steer the car to avoid obstacle in front especially during wet condition.
Troubleshooting a problem on the ABS system and fixing it is very expensive so be ready to put out more cash when you bring the car to a repair shop to get it repair. But you have an option of skipping the repair since the car is still safe to drive without ABS, you only lose the advantage of safety it provides when the situation is deemed necessary.