Do you mean the ABS light? Make sure the brake fluid level isn't low, if it's not the low fluid warning lamp it is likely the control module for the anti-lock-brakes starting to go bad, which is very common. There are places online to get rebuilt ones, or you can try swapping in a used one if you can find one locally. It's the black unit on top of the ABS block with 4 torx head screws and it pops right off.
If you are handy with electronics you can try to pop the top cover off (and by pop I mean you have to pry the everliving shit out of it to get it off) and re-flow the solder joints where the electrical contacts are soldered to the circuit board. I believe all the rebuilders do when they repair them is to re-flow the failing solder joint to one of the ground pins. The power and ground leads are the larger contacts, all the other little small ones are the signal leads.
(Former) Saab Tech / Competition Prep