[HawkX66]

The simplest way to see if it's a ground issue is to run a separate ground. You could run a separate wire from a known good ground contact directly to the wiper case/ground wire. If when you turn the wipers on they aren't working, then you hook up the ground and they work, you'll know it's the ground. From there, you just find where the ground circuit has been broken. Broken wire, loose screw, rusted ground contact etc...