Appreciate the commentary. The turn signal stalk does seem like the most likely culprit. The failure mode is not repeatable however. The wipers often come on with no interaction with the turn signal lever. Often the turn signal lever works as expected with no failure. It does fail most every time I use the vehicle to go somewhere.
It just seems to be getting a false signal to the wiper control input going to the processor or circuit. It could be caused by:
- the faulty wiper switch
- bad ground, system noise
- loose wire or contact to the wiper switch
- input to/from the rain sense control line (this truck does not have this option) is floating or not terminated properly
- software signal is telling the wipers to come on, however I can get them to go back off by cycling the wiper switch
These are my best theories at this point.