antilock brake module,1994 mitsubishi 3000 gt

the antilock brake light has come on and won't go off. I can hear the module running and
won't turn off. Even when the car is turned off you can hear the module , its kind of a
thrum noise.  I had to disconnect the battery to get it to turn off.  . Whats up , this had
actually happened last year, after being disconnected  it went back to normal , for a year.  
Very strange.