The ABS Light has just started coming on. What is the cause? Do I new brake pads on 2004 Lincoln Town Car

The light came on practically as I left the dealership from replacing a new Fan Motor and assembly. Is it possibly something they have caused? I have never had a problem before.

Asked by for the 2004 Lincoln Town Car
scan test for codes could be a bad wheel speed sensor
Thank you very much. I believe I will be in need of a Brake job as well as testing all sensors.

Larry D. Roy