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85+ Motor has a Delay Board on it
under plastic cover and many times the board is bad.
"Fix Kits" or whatever to fix the board may work but often doesn't help now or down the road. Get New board from any part stores often as a "Dorman
Sometimes is the Column Switch or maybe both. new switch are not made but can use a "updated" part from another GM trunk. use search.
Note that Motor often have issues/problems that can kill those new E-parts.
1. is iffy motor ground. Is a thin metal "shim" hold by pressure from a "rivet" in rubber mount "bushing." Rubber and/or shim gets crap or rots after years and need work to clean at minimum.
Part of why here...
See my Cave, Electric Motors
2. Motor may have iffy bushes and switch that kill the E-part too. Use search how to test the motor w/o the board. Do Not test motor in the cars on Dry Glass or can wreck the glass, wipers, and other Wiper parts.
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
The Ogre's Fiero Cave