wipers not working

[rasouth]

I have a 1996 Explorer, 4.0, 4WD. I cannot seem to get the front wipers to work. I have checked fuse with multi-meter, checked relay, switched relays, replaced multi-function switch, tested multi-function switch, replaced wiper motor, checked for continuity between each wire connection from switch to GEM to fuse to relay to motor... I seem to have power into the Wiper HI-LOW relay and over to the Wiper RUN relay but that is where it stops. In the diagram I have it looks as if the power feed would go from RUN relay back into the HI-LOW relay and into the White Or Dark Blue/Org wire feeding the motor with a signal. I was told that if I grounded the Yellow/ Wht wire from GEM and wipers worked then it was a GEM problem. I tried it and it worked... So I found another GEM from an auto recycling place, same year, model... I had same problem, so I started looking elsewhere for the problem. The replacement GEM was taken from the car itself. It came with backing plate and wire harness still attached, so not an old, replaced one. Maybe... replacement GEM had same problem. Don't know. Is there a way to test the GEM itself?
And... Does anyone know where the ground wires, (two black wires), from wiper motor are attached to ground? I would like to rule out any ground issues.