If it is the red indicator light, check all ABS fuses. There are two locations, under the hood and inside (side of the dash when you open the driver's door) I had this happen and one of the abs fuses was blown. If the fuses are ok, try operating the park brake lever. There is a switch on the park brake that also activates the indicator light when it is applied, and it could be broken or not functioning properly. try those before going the route of a new computer as the computers rarely go bad.
If it is the orange ABS indicator light, take it to someone who can run an ABS scan for codes and work from that.