ABS light is always on

Many times ABS problems can be attributed to a faulty WSS (Wheel Speed Sensor). These sensors are typically located at each hub, behind the wheel. They can give incorrect readings due to corrosion or brake dust build up on the sensor ring or, being an electrical component, just go bad. Some repair shops will have a dedicated scan tool to check each sensor. To check for these conditions yourself, you can trace the wiring that goes to each hub, noting any damage. On the front two hubs the sensor ring ,which resembles a gear, is located on the end of each drive shaft (CV shaft). On the rear they are typically incorporated into the hub assembly. You can use a DVOM (Digital Voltage Meter) to check each sensor as well, however this can be a little involved if your doing it alone on a floor jack on the ground. If the problem is discovered through whatever means to be in the rear, expect to have to replace the hub assembly, as most of the time the ABS components are part of the assembly itself. The other way to look at it is, if you've been driving for two years with this condition, as long as the base braking system is ok it probably isn't going to be that much of an issue to continue as you were. I'd still get it checked out though. Hope this helps.