GM-GMC: wipers, aluminum heat sink, salvage yard

Question
Hi there,
I have an 89 GMC K2500 with intermit. wipers.  The crazy things will just stop on me for no reason at times and then at other times I turn them on and can't get them to turn off.  There are even times I can't get anything to work including the sprayers.  The turn signal wand controller was replaced about 2-3 years ago for the cruise control repair.  I used GM part. Where to start?  Wiper motor?
Thanks for your time.  Mark

Answer
I would try changing the pulse (intermittent) wiper control module.

This is a module with an aluminum heat sink that is connected to the wiring harness coming out of the top of the steering column.

It is usually somewhere above the steering column but is also found off to one side or the other.

A salvage yard may have the part, or a column that you can look at to see what the module looks like.