Probably because the park switch in the motor is bust. This supplies the motor with electricity (after you switch off the wiper) until the wipers are parked (i.e. returned to off position).
The wiper motor doesn't turn off until the wiper arm gets to the "park" location. If the wiper motor never detects park, the wipers will stay running.
The 1996 Buick Park Avenue has the most common hook-end wiper arms. See sources and related links below for installation videos. Also, purchase the replacement blades first and there will be additional instructions/illustrations on the replacement packages. Locate and press the tab or button where the wiper blade is inserted into the hook of the wiper arm and pull wiper blade out of hook. You may have to rotate and flex the blade to make enough clearance for the hook to pass through.
Usually it is part of the wiper motor.
Discovery Park - Purdue - was created in 1961.
Welcome to Discovery Park was created in 2001-05.
Jurassic Park Discovery Center was created in 1999.
Discovery Bay Coastal Park was created in 1979.
There is a Discovery Park on the Park shores of Seattle, a neighborhood called Magnolia in Seattle Washington. There is also a park in central Sacramento, California.
Its in the fuse block under the hood located on the passenger side just in front of the wiper assembly ...
Either the park switch (usually within the windshield wiper motor) is bad, not letting the wiper park, or the intermittent wiper control is bad, not letting it shut off. Another possibility is a bad ground.
The self park wiper was introduced with the Mini Clubman and 1275GT models in 1969.
It's possible that the wiper switch is bad, but most likely it's the wiper motor itself. Wiper motors have an internal switch that only turns off when both the manual switch is turned off AND the wiper blade is in the park position. If the wiper motor cannot sense that it has hit the park position, it will run continuously.