if your abs light is on already the abs is NOT WORKING NOW, no need to unplug anything.

and the brake shop ain't going to scan your abs for free, its a $100 scan at best, unless you got a friend there. or you leave it there for them to fix it.

jack up your car and see if you have the any play in the wheel by trying to move the wheel from 12 o'clock to 6 o'clock, if it has any movement, thats most likely your bad hub, and see if the wires are worn through or if the plug fell off the hub on all 4 wheels.