The multifuntion switch (dimmer, wiper, turn signals) are different for different years. 87-98 will work in any 87-89 car. The 90-93 switches only work in 90-93 cars. You can't put an early model switch in a late model car, nor can you put a late model switch in an early car.
I've had the same problem for some time now, and its not the multi-function switch, I know I used the right one. There has to be something else that controls the wipers between the switch and the motor. Does anybody have any ideas what it is and where it might be?
There is a wiper govenor control box under the dash where the column bolts to the dash, I think this is the problem, after I get a new one I will let you know.
i had the same problem this weekend, its the govener.....about 90 bucks, its a lil brown box under the dash under on the driver side. check the threads from a few days ago....