'97 Sierra Wipers Not Working

I have a 1997 Sierra and occassionally the wipers will not work. I can hear a "grinding" noise and if I rap on the plastic cover over the motor gear they will usually start working.

Do I need to replace the motor or is it something else?

The grinding noise and the you rap on the wiper motor cover and it works from there?
Sounds like you should try the wiper motor replacement, but I think maybe a switch? Of course I could be wrong

Same thing happened to mine. I replaced the board inside the cover that you are talking about and it fixed it. Make sure you put some kind of sealant on the cover to keep moisture from getting inside. Moisture is the reason the board goes out.

Same thing happened to mine. I replaced the board inside the cover that you are talking about and it fixed it. Make sure you put some kind of sealant on the cover to keep moisture from getting inside. Moisture is the reason the board goes out.
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There was a recall on the wiper motor circuit board. seems the printed circuit wasn't soldered well. They replaced mine a few years back.
Bob B

Put a ground wire on it and this one is the fix.GM never thought of this at all.All you need is a short wire and two ends and one self tapping screw.Put one end on the firewall and one on the wiper motor.

my 98 does the same thing, seem like whenever it rains. i took off my wiper motor and tested it and it was fine. so i took off the wiper cowl and covered the wiper linkages with lithium grease. it seem to work for a few months then i had to put more lithium gease on it. its a 3 dollar fix thats worth giving a try.