[tmaster1187]

Had the same problem on a Chevy Silverado. The sensors in the hob sometimes go bad or need cleaning. There is a little metal(can't remember if the metal is magnetic or not) that reads how fast the sprokets inside the hubs rotate past it. If you are not getting any kickback in the brake petal it might just need cleaned, espically from where it probobly sat still(being wrecked) before you bought it. If you are getting kick back then the sensor might be bad alltogether. If you clean and/or replace in and it still does it then the abs "brain" is bad and you might have to replace it. Not sure on prices or ease of access to the sensor.