Power window motors draw a lot of current. For that they need clean and tight connections and larger wiring.
A common issue is grounds and switches.
Check where the harness grounds to the body of the vehicle. Usually the wiring for the motor goes back into the cab to get a good ground.
Switches tend to get debris and contact burn. Removing the switches might find if they are dirty. Clean out. Or you could run current directly to the motor to see if the motor works. If it does the motor is good and the wiring/switches are the issue.
Thanks for the reply. I know I am going to have to spend some time checking all this out. Going out of town this week so will be a couple of weeks before I can get down and dirty, going to get to the bottom of this, probably something simple
Diagnose the issue with a voltmeter and wiring diagram.
Dirty contacts on switches
Poor connections in the harness
Not sure how a relay appears OK as usually this is a sealed metal container. Depending on year, newer vehicles you might be able to swap relays of other systems
Please create a new thread if you wan to post more. This is a two year old thread about a 98 F150 that the OP never completed.