Check the ground for the wiper motor.  I had to repair the ground in my 81, which I doubt is the same in yours, after removing the motor, bench testing it, cleaning the switch, then rebuilding the switch, by passing the intermittent wiper relay and finally buying a new switch and installing it.  Ground at the motor was the real culprit, although the switch was in bad shape too.

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Dave C..........My mantra: I can not be bought!!      Long and short term leases available.

I feel your pain.  There are so many interlocks that have to work to get the wipers to run.  I was out to dinner last Wednesday with our Corvette group.  It started misting a little before we all left.  I opened my wiper door with the pull down under the dash so it wouldn't close when I shut off the wipers.  But the wiper wouldn't work.  They worked 6 months ago as that was the last time I tried them.  Tried them again a few times on the  way home and no deal.  Now I pissed and ready to sell the damned car.  The gas gauge quit working the week before and the power steering return line started leaking bad the week before.

I get home, pull in the garage, and just for fun I try them one more time before shutting down, and you guessed it, they worked. 

You might try pulling the wiper door as far open as it can go to trip that switch.  I still don't know why mine didn't work and then did.




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Thanks for the hint. I'll look at the ground.

|UPDATED|2/13/2015 3:57:43 PM (AZT)|/UPDATED|

Finally, it is clear that the black cable that connects to the wiper switch is not grounded.

The wiper switch controls the field connections to determine the motor speed, slow or fast, so the earth comes from the switch, if this is not the case then there is a fault with the switch body to earth usually due to a bad earth to the switch bezel, try running a separate earth to the switch body.

|UPDATED|10/28/2015 8:00:33 AM (AZT)|/UPDATED|