Raining so NATURALLY the wipers quit. ('90 Dakota)

'90 2WD, 2.5L 4cyl - Wipers quit but washer still works so not a fuse as they are on the same one. No sound from wiper motor so linkage/pivot arm not the likely culprit. I figured it was wiper motor, hands down. But a parts store guy started yammering about a "wiper motor pulse board module." I can find NOTHING online from either of the area's two main parts dealers about such a part. Other possibility could be the switch on the turn signal lever.

Anybody got any insight (either about the switch, motor, or that mysterious "module") before I go throwing money and parts at it?

Thanks,

Karl