Wipers have mind of their own

I have a 1990 GMC sierra 1500. The wipers come on when I need them to but for some reason they dont always shut off. I find it happens more often when there is only a fine mist. I will put them on delay and it switches to low speed on its own and even keeps running when I try and shut them off. What should I try first? Is it something I should just take it to the dealer for (Recall maybe that I didnt know about?)
Thanks, Dave.

When this happened on my 90 K1500, I took the circuit board out, cleaned the connections really good, used some dielectric grease on them, put it back together and I never had the problem again. That was a couple of years ago.

The circuit boards do go bad. No recall that I know about (original owner on my 90). Try cleaning the connectors first and go from there.

//2000CAYukon

There's a recall on certain models. Stop by the dealer and see if yours is one.

I have a '94 that had the same problem, went to the local auto parts and bought a new board, that fixed the problem. They are under $40 now.

I just re-heat the solder joints on the circuit board--that usually last about 4 years each time- but the price is right!

when this happened on the 1994 SLT sierra and the 2000 SLT sierra (crew) and the 2002 SLT sierra we replaced the little circuit board inside the wiper motor

I was wondering.....My wipers are doing the same thing and also the washer motor is not working when applied....Could a bad pulse board module also affect the washer motor operation ??

Thanks

another quick fix is to install a short ground wire from wiper motor to firewall . i think the board loses a ground. mine has worked for about 8 years now