My abs light is on. I hooked up the scan tool and it gave me a 555 code with no description. I asked my teacher and i asked the guys i intern with at the local ford dealership. they have never seen a 3 digit code. i dont know why its doing it. the light wont come on tell a mile down the road. Then it acts like the abs is kicking in. and then the pedal sinks farther than usual and then it is like that for the rest of the time. I am running a smaller tire on the front than on the back.