Not sure if this has been covered, I did a search and found nothing. I have an 04 AWD Endeavor that has recently started making a weird noise during braking. It's a bizarre high pitched noise that I can only describe as a "woop" and it only happens at low speeds, especially when backing up or coming to a stop. If I had to guess, I'd say it had something to do with the ABS. It's not a grinding or a rubbing; it's almost like a hydraulic noise. Really odd. It's doing it more often lately and I'm trying to figure out if it's serious or just an annoyance. Any help would be appreciated.