During the 1-7-12 show, a caller asked a question concerning why his windshield wipers are “parking” themselves in the up position when turned off.
This is caused by a broken Windshield wiper transmission (not the motor). The wiper motor turns in a single direction during normal operation, the wiper transmission translates this rotation into wiper oscillation. When the wipers are turned “off”, the wiper motor runs in reverse for one turn. This reverse rotation “should” activate a cam in the wiper transmission which causes the wipers to retract into the plenum or onto the hood.
If the wiper transmission reverse-cam doesn’t engage correctly, the wipers will not retract. Instead, they will run in reverse and stop in the “up” position when turned off. I have seen this happen when a small spring clip designed to hold the “reverse cam” in place breaks causing the cam not to engage. Although it may be possible to rig a fix (rubber band? paper clip? etc), the sure fix is to change the wiper transmission assembly gears and all.
I learned this the hard way after changing the motor and realizing I had the same problem. I found a replacement wiper transmission through an online junkyard for ~$30. Took me about an hour to replace.