Okay, I took your advice to heart. Removed both headlight assemblies, re-soldered all three ground terminal wire assemblies and wire brushed the body connection area at the ground screws. Still getting the same problem.
Have also noticed that turning the headlight switch one notch counterclockwise to the right side valet parking position will cause the wipers to start when the ignition key is in the accessory position but not in the run position. Turning the headlight switch clockwise to the parking or headlight position will cause the wipers to start if the key is in either the accessory or run positions.
Have ordered a factory electric troubleshooting manual.