If you have a mate with a workshop that has 1 of those snap on tools ecu scanners it will tell you the exact problem, had to do a front speed / ABS sensor on mine recently, would make a noise up under the dash somewhere like when you turbo the heat from cold to hot or vice versa, and then the ABS light would stay on until I turned car completely off and turned it back on, would be ok for awhile then same thing, just to let you know, when the ABS light comes on be aware your ABS wont work at all, mine used to do the big single wheel brake lockup whenever I jumped on the brakes to test it...