Topic: Wipers won't work - fuse is fine - why?
in Forum: C3 Electrical, Body and Interior
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Now that the vacuum controlled wiper door works fine (after replacing a defective vacuum relay), I can't get the wipers to work anymore. I checked the fuse: It's fine. I can only get the wipers to move (just a little) when I push on the switch on the dashboard (as if asking for windshield wash): They move a couple inches out of their lodging and back, although not fully. However, I can't get them to work either in low or high speed.
That's weird because they were working fine before I replaced the vacuum relay (except that the wiper door would stay open all the time). And when I tested again after replacing the relay, they worked once, only once, and stopped for good. Again, the fuse is good.
Any hint is welcome.
Christian
1971 LS5
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Ash Fork, AZ - USA
Joined: 4/18/2007
Posts: 1058
Vette(s): 1981 Red Interior White exterior
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.
Hope this helps some.
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Lifetime Member #192


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.

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.

Thanks for the hint. I'll look at the ground.
|UPDATED|2/13/2015 3:57:43 PM (AZT)|/UPDATED|
As to the wiper door, that's one of the things I have checked and tried already. Not much success. Thanks anyway.
|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.
I am able to make the whole things work by grounding the middle pin of the switch directly to the frame of the car.
I can't figure out where the black cable is disconnected.
Former Member
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United Kingdom
Joined: 10/6/2015
Posts: 83
Vette(s): 1970 convertible in red 350
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|
By the way the reason you have 12v at the blue and the yellow for the pump is the power passes from the yellow through the coil windings to the blue wire, if you disconnect the wires there will be 12v on the yellow and the blue will be to earth only when you press the washer switch.
Hope this helps, I've just been through this process on mine and in the end fitted a universal pump to the blue and yellow to get washers as the original pump is not working, something to play with over the winter.
Regards
Graham
|UPDATED|10/28/2015 8:00:33 AM (AZT)|/UPDATED|
in Forum: C3 Electrical, Body and Interior
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