Air Brake Antilock problems of the 2000 Ford Ranger

Abs light had been turning on and off for weeks and brakes had not been functioning properly. Then light was on all the time. At intersections I would apply the brakes and they would barely stop the truck. Once it was stopped the truck would then suddenly roll forward again even with brake pedal pressed to floor. Front and back pads were replaced by my mechanic. Problem still occurred, especially when going down hill. Took it back to my mechanic and was advised to take it to the dealership since it was not the brake pads and was still under warranty. Rude service rep at dealership went with me for a test drive, said he could not verify my complaint even though the abs light was on for the whole ride. He claimed my mechanic had screwed something up, said the intermittant brake failure was all in my imagination, etc. But since it was a safety issue he would do further diagnostics. Two and a half weeks later after bad customer service the truck's "non-existant" brake problem turned out to be water collecting under the driver's side seat and rusting out a sensor for the abs system. Entire abs system replaced. Problems solved for now but what about when it rusts out again? why had water collected there? I do not drive in rivers or lakes. It would have cost me $2500 in parts and labor if it had not been under warranty. Dt.

Abs brakes lock up. Dealer declares brakes safe, brakes lock up and are not pumped or "slammed" ,,, standard pressure causes brakes to lock up - occassionally.