Why does my winshield wipers go on high speed only? on 1993 Ford F-250

changed motor,switch,module and nothing seemed to correct the problem. The wipers use to work properly but just started doing that several months ago. I don't know where to go from here. Anything that you can help me with that I haven't done would be greatly appreciated.

Asked by for the 1993 Ford F-250
Your truck should have a wiper pulse board but not sure if that's part of the module that you already replaced ?