I can't find the prob. The windshield wipers work fine in all modes...
but when they are shut off ...they will activate in a single sweep ,once about every 3 minutes, and that's in the OFF position. Someone Please let me know what's up. Also the interior lights under the dash won't go off. Oh, this is a '90 Sierra 1500. Thanx!!!

Are yoy any good with a soldering Iron? If not you need to replace the motor. Had the same problem on my 92. Take the cover off carefully, and look for bad solder conections.

More than likely the washer assy (which controls the delay etc) is the culprit. NAPA has one for around $30 and takes less than an hour to install. Email me with any specifc questions.