Wipers wont shut off - 89 Caprice

I have a 1989 Caprice Station Wagon. All of a sudden the windshield wipers will not shut off, once I turn them on. I have to unplug the cable going to the wiper motor. Then it shuts off until I use the
wipers again.
What is causing this? How can I fix it? (hopefully without repalcing the wiper motor). Wipers do work ok except for this.
Thanks
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There is a known problem with the pulse board on GM products that can cause this problem. I had it happen on an almost new Oldsmobile company car of that era. In my case,the company shop did a repair on the pulse board. It had nothingn to do with the motor itself.
I think you may still be able to get the replacement boards.
I had almost forgotten this problem which should be added to my bitch list of GM shortcomings.
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We had a '91 Caprice 9C1 (police) that did this. We always just shut the ignition key off for a split second and turned it back on to kill the wipers. Since the 700R4 isn't electronic if we were going at highway speed the wheels would keep the engine turning and we could be slow about it, in town you had to be quick unless it was manually downshifted.
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On Sat, 18 Sep 2010 14:11:57 -0500, "Daniel who wants to know"

Thanks for the info. I'll see if I can get a replacement board (I assume it's inside the wiper motor housing). If not, the key idea sounds good, and I was thinking to cut one wire going to the motor and put a switch under the dash to shut it off. But getting the right wire may be tricky.
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I dont think that shutting off the ignition key while driving is a very good idea at all.
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I'm not fond of the idea myself, but it's either that, or pulling over to unplug the motor wire. I suppose I could pull over and shut off the key. However, I plan to install an under dash switch, unless I can get a replacement board. They want almost $100 for a rebuilt wiper motor. I can get a under dash switch and some wires for less than $5. So, I think the switch wins. Now, I only have to determine which of the 3 wires to cut to install the switch. ????
It's an old car, so I'm not going to spend a lot on a wiper motor that still works, just wont shut off.
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It is not likely the wiper motor that is your problem.. The pulse board controls the variable speed wiper, and these boards from GM are known to have weaknesses.
I believe you can find a new (aftermarket, thank goodness) board for less than $30 online.
I'll google it for you if you wish.
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I seem to remember the wiper boards had a cold soldier joint issue. A resoldier was the cheap fix. I may be wrong though YMMV
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I dont think I ever heard exactly what the problem was. They had some semiconductor problems during this time span on window control board, computer, etc but dont know if that was involved with this. You know, pulsed systems can be a bit hard on components if they are not well done.
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