I own a 1999 Ford F-150 2WD V6 manual transmission truck. One year ago I had the windshield wipers turn on at random times and random intervals. The problem gets worse when I accelerate, also when the weather gets cold in Los Angeles and when it rains. Even if the setting is OFF the windshield wipers would act crazy and I can’t turn them off. Online F-150 owners seem to address this issue as “ghost wipers” and they offered several suggestions: replace the multifunction switch on the steering column, if that does not work then replace the wiper motor altogether. I first replaced the multifunction switch and the problem remained, then I replaced the wiper motor and the problem was temporarily fixed until 2 weeks later when during a rain storm the problems started again… Any suggestions?
Another possibility is the wires in the gang plugs at the multifunction switch.
Some times the liitle tines that keep them in will break off and the wire end will not make full contact or even come partially out.
Next step , the fuse box under the dash.
Not just a ‘‘fuse’’ box any more, sometimes call a smart junction box.
It now has multiple layers of sandwiched ciruit boards in there and moisture intrusion and even dry residue can cause shorts.
The GEM module on the fuse box houses the delay function.
Did you check the wire harness for chaffing and rub through ?
GM has had this problem for many years,perhaps it is resolved by now. We called the problem “phampton wipe” replacing what GM calls the “pulse assembly” fixed this problem on GM vehicles.The pulse assembly is the group of electronic components that make multiple speed wiping possible.
Another possibility is the wiper relay in the underhood fuse block. I have replaced several through the years on Fords over similar issues.
Hmmm… When I replaced the wiper motor I didn’t think of checking the wire harness for chaffing… It would explain why only when it rains the whole thing acts so crazy…