Hello everybody,

It must have been more than a decade ago that I visited this great forum. Bought a 1972 C3 in 2007, drove it a few years and ... life got in the way.

Anyway, I'm back and I would love to start restoring the car. I want to start with the electrical stuff, want to try and fix everything in the car, but I don't know much (nothing) about electronics. I have been reading lots of forum threads, watched some videos and I'm now trying to do the wiper motor test (as explained in the WILCOX video and other youtube videos). But I'm experiencing something funny with my motor. I connect the positive terminal of the battery to nr 2 and nr 5 (see pic below). Then I ground the motor by connecting nr 4 to the negative terminal. If I understand correctly, nothing should happen now. But once I connect the ground, the motor starts turning on high speed. When I connect a negative to nr 3 and than another neg to nr 1, the motor runs slow speed. To me, it seems I can not park the motor.
I have read that when the wiper motor always runs, something is wrong with the ground, but in my case, since I'm testing the motor seperately, what can I do wrong with the ground connection? Any ideas? Is my motor broken?
Honestly, I haven't been able to open up the motor yet as I don't seem to have the correct measurement wrench (ordered it), hope to have it tomorrow.

And also, I noticed bubba (although I guess I'm the biggest bubba of them all) connected both the wires (see circles on the photo) together. I don't know why, but I removed that connection.



All help welcome.

KR,
Maarten

 

Metal Case (your #4) to ground
Single red wire (your #5) to positive
Yellow wire (your #3) to positive (keyed 12v)

Park = Green ground, blue not connected
Low = Green ground, blue ground
High = Green not connected, Blue ground

M

 

Hi Mooser,

I have been reading lots of forum threads and see you are an expert on this thing. Thanks for trying to help me.
In your explanation you say : Yellow wire (your #3) to positive. --> I think you mean #2, right?

Anyway, my problem is, with both #5 and #2 connected to positive, from the moment I connect #4 to ground, the motor starts spinning in high gear. I haven't even touched #1 and #3. Which seems odd.

But I have another question. In this video, which explains it also a lot, at around 04:50, you clearly see only #2 is connected to positive : . There is no #5. Is this another type of motor perhaps?

Anyway, I hope I can open up the motor this week to further inspect the PARK mechanism and make a video to explain it a little better.

Thanks again for your time.

Maarten

 

I'm no expert in anything.
Yes, sorry, my colors and where they go is correct but not the reference to your pins



For the parking, if it's not CLICKING then the electromagnet inside if faulty or has a broken wire. There might be some information of use here
https://www.corvetteforum.com/forums...-assembly.html

M

 

Thanks so much Mooser. What a great thread. I'll get back to you on this once I have opened up my motor.

 

you have to ground the case, not just the wires. You also have to have a drag on the motor for it to park when its slow and the correct wires are grounded.

 

this is a better test video...

 

Thanks a lot for all the hints and tips. I hope to have the motor opened up soon and ready to test. I will keep you all posted.

Maarten

 

There is probably nothing wrong with your motor. Set it up so it's running slow in the park setting, when it moves down into the park position, trip it with a tool by closing the lead to trip the switch. These motors do not park without drag on the motor to stop it in the park position. It says it in the AIM. Without the wipers connected you have to put weight on the wiper shaft to simulate it parking. If you manually trip the park switch and hold it open and it does not stop, then you have to replace the park switch.

Your motor runs, there is nothing wrong with it. It runs in 2 speeds, there is nothing wrong with it. I told you you need to ground the case and the ground lead. One ground is not how these are wired in your car

 

ttt

 

Cleaned the outside and opened it up. Hope to test it this weekend. Just had no time this week. But you already see it is not in park.

Thanks for all the feedback.

 

i thought you were going to take it apart. What you removed its the washer pump. if you hook it up for a bench test you just need a small probe to push down on the park switch in that small slot while its running and it should stop. Its just a spring loaded switch. If it does your motor is fine. If not you might be able to find a corvette park switch but it has to have those 3 tabs on it. There are some on Ebay but they arent quite the same

 

So today was a learning experience, I guess. The motor WAS working perfectly, as seen in this video : https://www.dropbox.com/scl/fi/hls6y...=v01yvmp0&dl=0

Only on high speed we noticed smoke coming out, so I started cleaning : https://www.dropbox.com/scl/fi/0ygk4...=epa7lufc&dl=0

more cleaning :


After cleaning we did another test, smoke was only appearing when everthing was put in place, not with the parts hanging out. We noticed is was here, where the little wire (also a ground I think) was in contact with the plastic casing :



So we added a little 'firewall' :



We did a new test and on high speed, the smoke now was gone.

Finally, I also noticed a little red wire on ground #1 was not nicely attached, so we resoldered it.
We also fixed the main 12v wire (see circles on pic of first post).

I did a retest, once I connect #1 to get the motor started, it smoked everywhere. I think I made a short somewhere after the soldering. Maybe with the soldering of the little red wire underneath #1.

This is how it looks now :



Smoke also came out of the main spindle of the motor. I opened the motor to see if anything was burned, but no. Now everything is in PARK position. I would like to remove everything again to have a closer look, but I don't know if it is possible to manually unpark it?

I think the thing is gone, but I wanna look anyway.

Yes I feel stupid now ...

 

once you get the park switch back out you may see where it got smoked. I think you can fix it again. If the resistor is still good as welll as the relay switch you should be able to bring it back

 

I'm a little late to this conversation, but I updated the GM drawings on the wiper circuit.
You may already be past the need for it, but you can never have too much documentation.
It says 1969, but the wiper motor was basically the same for years.

 

Ok, motor is completely dead now. Where can I best buy a replacement these days? Or anybody on european soil has a working one for sale? Let me know.

Thanks.

 

I just bought one from Lectric Limited....you can look on ebay in your country and hope to get lucky. Save your park switch. It might be good

 

Hello fellow C3 lovers,

I finished my fuel tank and sending unit and am now back on the wiper motor. So I bought a new one. Before installing, I check the power cable and ground under the hood, tested it, did not bench test the new motor, installed it and I had a problem. The motor doesn't want to go in park. Thought it could be a problem on the switch, so I took the motor out again and did a bench test, see if I still had the issue. This is the result (please ignore the Dutch mumblin' ) : https://www.dropbox.com/scl/fi/t418p...=6l66uoyb&dl=0

So as you can see, it seems like a park issue. And I checked on youtube and on the forum, and sadly, it seems a bit common? The only thing for me that comes to mind is cleaning the park mechanism, remove excessive grease and hope for the best. Any other ideas?

Thanks,
Maarten

 

If you put the linkage on it it will park. It needs the drag of the wiper system to slow it down

 

With linkage you mean the actual wipers? Could be, but still weird, normally the park should work in a bench test. It did with my old motor before I burned it...