my wipers dont work all the time i thought it was the motor changed it same problem if it is damp out they seem to work if it is cold and dry there is nothing when they work all the speeds work fine when its not none of them come on idont know if its a ground or in the wand i drilled the end of the wand and shot a bit of contact cleaner no different im about ready to give up considered running power to the wiper directly mine is a 94 with 2 plugs with 3 leads each any ideas ....

 

Try this first and see if it fixes it: https://www.f150forum.com/showthread...control+module