1999 gmc sierra wipers will only run on high. Any idea why?

anon
turn off the key (wrong)
or turn off the wiper switch (good0
or both, not told.'
here it is,
as you can see , it all loses power key off, as in ALL DEAD.
BUT IF YOU TURN just THE WIPER TO OFF. AT ITS SWITCH
IT MUST TURN OFF. AND AUTO PARK (switch not bad)
THAT MAGIC HAPPENS BY THE YELLOW WIRE BELOW RIGHT SIDE.
so yellow wire busted.(mice eat it, IDK)
or wiper guts bad( the internal so called PULSE board)
marked control logic below.



THIS MODULE IS SOLD HERE.

https://www.rockauto.com/en/catalog/gmc,2002,sierra+1500,6.0l+v8,3300378,wiper+&+washer,wiper+motor+module,17720

Try checking the wiper switch

its hard to say but when you tilted columb could pinched a wire in the columb or the electrical part of the ign switch has gone bad suggest you take to your local mechanic either repair is quite involved

Yes it is the switch. If it were anything else the wipers would not work at all.

If you raise your hood and look at your wiper motor on the fire wall there is ablack plastic cover over the motor remove that and you will see a chip board that is replacable its usually around $20 or so, which is cheap way to find out if your wiper switch or multifunction switch is bad, since they arwe far more expensive! if the board does not solve your problem then suspect multifunction switch!

May want to look at replacing the wiper circuit board.It is located on the firewall adjacent to the wiper motor and has a some what square black cover with 3 torx screws and wireing harness pluged into the side.We had a truck that every time you washed it the wipers would stay on until it dryed out.You can try removing it and spaying it down with contact cleaner just watch the brease on the two contact tips.Well hope this helps.

sounds like a bad switch

no the day running bulbs go out during night driving

most likely the wiper board have failed, this is inside the wiper motor.

thats the wiper motor itself i change so many on gm vehicule thanks pierre