ABS Brakes Help!!!!!

i have a 99 Contour SE 4 Cyl. with ABs problems. i hit the brakes at low speeds and the ABS kicks on. Sometimes it happens at high speed but mainly at low speeds. is this a brake job or an ABS problem? I also have a fan motor problem. I have a new realy switch but have no idea where it is to replace it. Any help would be appreciated. Thanks!