2005 Ford F350 Wiper problems
 

I have a 2005 F350 Forn Larriat and I have wiper problems. They do not work.I have replaced the wiper motor and the plug in pig tail and still nothing. I have also cleaned the contacts in the wiper arm. If I put a ground wire on one of the wires for speed or water on the motor it will work for a bit than quit. I am at a loss for what the problem is. PLEASE HELP.