As a Silhouette owner, I get worried every time I see a GM minivan with it’s wipers sitting somewhere mid-windshield when not running. If this ever happens to me, what should I look for?
The first thing to check for is a defective pulse board. This electronic component is what conrols all the wiper functions. It’s located under the wiper motor cover.
I own a 2000 Silo and wondered the same thing and do see some GM vans with this problem.
When I bought mine I also bought the Haynes Repair manual (1997 thru 2001 all models GM) #38036 to learn how to fix this and a LOT of other components in/on the van.
For $20 it’s worth it.
To answer your question: If the wipers stop at the position they’re in when the switch is turned off (Fail to park), disconnect the multi-function switch electrical connector. (This is located under the dash next to the firewall and steering column)
If the wipers now park, replace the multi-function switch. If the wipers still do NOT park, check the wiring from the wiper motor to the switch for a short circuit. If the circuits are good, replace the wiper motor.
Note: There are other adjustments needed for proper operation than just bolting and new motor on.
You can have a look at this manual at any automotive parts supply store.
I’m not sure if this is still true with something this new, but on the older cars with the wipe-towards-the-center style windshield wipers one of the wipers HAS to stay on top of the other one or else the wipers will never get back to the “park” position and/or the motor will burn out because the linkage is designed in such a way that the lower wiper has enough mechanical advantage to push the top one out of the way, but not vice-versa.
For example on my '64 Buick, the right blade HAS to rest on top of the left blade or else they’ll get stuck or once they get going they can never get back to the park position. It’s a much older car, but I assume the linkage works pretty much the same. I wouldn’t be surprised if the issue is that GM minivan owners change their wiper blades or even just wash their windows and set the blades back wrong.