Volvo Repair: Volvo ABS light, wheel sensors, abs light

Question
What would be the problem with my 1993 Volvo 850, it always has the ABS light on.  But i have no problems with the brakes or anything else.  What could it mean, and how can I fix it?

Answer
Tim, 93 was a stand alone year on pretty much everything.  It could be anything from dirty wheel sensors to a bad control unit.  The only thing that means when the light is on, you will not have the ABS functions but regular braking, you are fine.  It will be expensive so you decide.  LEt me know what you decide. Roger