False activation of the ABS (particularly at low speed) is often caused by buildup of magnetic debris on the speed sensors on the front wheels, or rust on the tone rings. Neither is very difficult to deal with, unless the sensor(s) are stuck in their socket(s). Usually, however, if it's bad enough to turn the light on, it will stay on until you turn the engine off, and go away when you restart it, so you may have something else going on too.

To clean the sensors, crawl under the front of the car, follow the cable that is clipped to the brake hose, to the back of the steering knuckle, remove the single allen bolt and pull the sensor out. Be careful not to pull or twist the cable. You will probably find it has "grown a beard" of iron filings and rust flakes. Wipe the tip of the sensor off and reinstall it, then do the other side. If you still have the problem after doing this, check the tone rings. Jack the car up, remove the front wheel. You may be able to see the tone ring mounted to the hub well enough to check its condition. You are looking for rust buildup. The teeth need to be clean and squared off to send a good signal. If they're not, you will have to unbolt the caliper frame (don't let the caliper hang by the hose--support it on something) and remove the rotor, then scrape the tone ring clean with a screwdriver.