My truck is a 1987 Dodge W250. I have been trying to diagnose a windshield wiper problem. These are pictures of the wiper motor and the black box that was clipper to it. What does this black box do? Are they prone to failure? Are they an available part that can be purchased?

 

I'm not familiar what they did in the 80's but i would suspect it's either the timer unit or a relay in the black thing. I would look up the wiring diagram and see if it has a external timer control box somewhere.