Windshield wiper motor

[MS66]

What would cause the wiper motor in my '68 to operate in the wash mode (push button) only? Is that more common to be a switch, or motor issue?

[dmjlambert]

What are you observing that makes you ask this question? I don't see how the stock washer can work at all unless the wipers are moving, because the washer pump relies on the wiper motor movement to actually pump.

[MS66]

Originally Posted by dmjlambert

What are you observing that makes you ask this question? I don't see how the stock washer can work at all unless the wipers are moving, because the washer pump relies on the wiper motor movement to actually pump.

The wipers only move across the windshield when you hold the wash button in. The wipers do not move across the windshield in either of the two, lo/hi, operating positions.

[67 twins]

Originally Posted by dmjlambert

What are you observing that makes you ask this question? I don't see how the stock washer can work at all unless the wipers are moving, because the washer pump relies on the wiper motor movement to actually pump.

He didn't say anything about the washer working or not. I would assume from his question that the wipers only work when he pushes the switch (wash mode) and not when he twists the knob (wipers only)
My assumption would be that it's the switch but that's just a guess

[dmjlambert]

I think it is likely the switch is having problems. You would have to do some testing with a test light or multimeter to tell for sure. Here is a thread about testing. http://67-72chevytrucks.com/vboard/s...d.php?t=413551

The back of the switch is swaged to hold it together. You can probably test it when removed from the truck with an ohm meter. It has 3 lugs on it, each of which should ground to the switch case when pushed or turned to certain positions. In low speed 2 of the lugs should conduct to the case, in high speed 1 of the lugs should conduct to case, and in how or high speed pushing the button should conduct the 3rd lug to ground.
Take the switch apart and clean it up with WD-40 or DEOXIT D5. Then put it back together.

[Zeke's Garage]

Yep, +1 on all that.

[Rust_never_sleeps]

wiring diagram here: https://67-72chevytrucks.com/vboard/...d.php?t=185856

[dmjlambert]

I'm afraid when talking about the wiper motor circuit specifically, most of the MANY diagrams in that thread have incorrect wiring in that area. You have to go specifically to post #344 of that thread. There may be other versions in that thread having the correct wiring for wiper motor, but most are incorrect. Unfortunately it would take a huge effort to clean out all the incorrect info in that thread. Here is a link that lands on post #344:
https://67-72chevytrucks.com/vboard/...27#post9186727

[MS66]

Originally Posted by dmjlambert

I think it is likely the switch is having problems. You would have to do some testing with a test light or multimeter to tell for sure. Here is a thread about testing. http://67-72chevytrucks.com/vboard/s...d.php?t=413551

The back of the switch is swaged to hold it together. You can probably test it when removed from the truck with an ohm meter. It has 3 lugs on it, each of which should ground to the switch case when pushed or turned to certain positions. In low speed 2 of the lugs should conduct to the case, in high speed 1 of the lugs should conduct to case, and in how or high speed pushing the button should conduct the 3rd lug to ground.
Take the switch apart and clean it up with WD-40 or DEOXIT D5. Then put it back together.

Took the switch out of the dash socket letting it hang under the dash just enough to poke out the bottom. Fiddling with the connector and got the wipers to work with the switch grounded to metal under dash. Did this several times. Pulled the switch out, cleaned it with WD-40, cycled it several times, blew out the residue with light air pressure. Lubed it with electronics lube. Plugged it back in, touched it to ground, wipers worked as they should. Did this several times. Wipers good. I'm thinking this is good, MUCH better than fiddling around under the dash killing my back to pull the wiper motor out (just to get nowhere fast).
Replaced the wiper switch. buttoned it all up. No wipers. Back to the same drill with the washer mode pushed in only. I came inside, I'll revisit that tomorrow. Thanks for the tips, although I didn't pull it apart to make it work. It seems like it was more something to do with the spade connections on the back of it than internal contacts. I have De-Oxit and Fader lube if I need to take it apart. I'm an old electronics nut too.

Originally Posted by dmjlambert

I'm afraid when talking about the wiper motor circuit specifically, most of the MANY diagrams in that thread have incorrect wiring in that area. You have to go specifically to post #344 of that thread. There may be other versions in that thread having the correct wiring for wiper motor, but most are incorrect. Unfortunately it would take a huge effort to clean out all the incorrect info in that thread. Here is a link that lands on post #344:
https://67-72chevytrucks.com/vboard/...27#post9186727

Nice schematic!! Thanks.

[dmjlambert]

Does your dash have new paint, particularly where the switch mounts in the hole? It's another possible thing, and pressing on the switch makes it contact ground.

[MS66]

Originally Posted by 67 twins

He didn't say anything about the washer working or not. I would assume from his question that the wipers only work when he pushes the switch (wash mode) and not when he twists the knob (wipers only)
My assumption would be that it's the switch but that's just a guess

Your assumptions are correct sir. Has nothing to do with the washer itself, just while in the wash mode. I do believe it is the switch. Will figger it out tomorrow.

Originally Posted by dmjlambert

Does your dash have new paint, particularly where the switch mounts in the hole? It's another possible thing, and pressing on the switch makes it contact ground.

No fresh paint. I'll figger it out tomorrow. Got to be something simple. I'm just proud the motor is operating. One less thing to deal with.

[MS66]

Originally Posted by dmjlambert

Does your dash have new paint, particularly where the switch mounts in the hole? It's another possible thing, and pressing on the switch makes it contact ground.

Ok, went back in there and noticed the alignment tang has something to do with grounding the switch. It had previously been in to, I saw it yesterday where it wasn't lined up just right and slightly hosed. I set the flat where it belongs in the flat in the top of the hole, tightened the 5/8 nut with an offset boxed end wrench, Voila! Grounded switch. Working like a new one for the time being. Thanks.

[Rust_never_sleeps]

interesting, I didn't see either the switch or motor connected to ground on the wiring diagram :shrug:

[MS66]

Originally Posted by Rust_never_sleeps

interesting, I didn't see either the switch or motor connected to ground on the wiring diagram :shrug:

Only18B at the cluster connector is grounded. I don't see the switch referenced in the schematic to see a ground, just the connector. Are you thinking these wiper switches aren't supposed to be grounded?

[LockDoc]

Originally Posted by MS66

Only18B at the cluster connector is grounded. I don't see the switch referenced in the schematic to see a ground, just the connector. Are you thinking these wiper switches aren't supposed to be grounded?

If the wiper switch isn't grounded the wiper will not work....

LockDoc

[MS66]

Originally Posted by LockDoc

If the wiper switch isn't grounded the wiper will not work....

LockDoc

Yessir, I know that. I pointed that out to the other fella, then asked if he thinks the switch isn't supposed to be grounded. Maybe I should have worded that differently. The switch is definitely grounded.

I've got my wipers all squared away now.
Thanks Leon.

[LockDoc]

Originally Posted by MS66

Yessir, I know that. I pointed that out to the other fella, then asked if he thinks the switch isn't supposed to be grounded. Maybe I should have worded that differently. The switch is definitely grounded.

I've got my wipers all squared away now.
Thanks Leon.

No problem. I just read it differently....

LockDoc

[Rust_never_sleeps]

Originally Posted by MS66

Only18B at the cluster connector is grounded. I don't see the switch referenced in the schematic to see a ground, just the connector. Are you thinking these wiper switches aren't supposed to be grounded?

nah, clearly they are, because it runs hot to the motor, so would have to ground somewhere past the switch....and because you fixed yours that way :-D
I'm just annoyed I can't see it on the diagram

[Jason Banks]

I have the exact same problem. Anyone have a theory about why it only works for the push? Does it somehow get ground that way, but not the normal way.

And then I found this thread:
https://www.67-72chevytrucks.com/vbo...d.php?t=695112

Post 15 Vette Vette is a treasure....

I had tried a new switch and that didn't fix my problem. So I thought! I took the new switch back out and put the old one in.

After reading this thread, I decided I would clean the paint off to make sure the switch was grounding and check with a meter to make sure it was grounded. It was. But still not wipers.

Dug up the new switch and reinstalled. Yay, I have wipers now!

[MS66]

Originally Posted by Rust_never_sleeps

nah, clearly they are, because it runs hot to the motor, so would have to ground somewhere past the switch....and because you fixed yours that way :-D
I'm just annoyed I can't see it on the diagram

Haha, I got ya. The only ground I see for 18B is past the cluster connector in the diagram. I'm guessing (??) that is the ground the wiper motor sees when the washer button is depressed?? Not sure. Sounds right though.

Originally Posted by Jason Banks

I have the exact same problem. Anyone have a theory about why it only works for the push? Does it somehow get ground that way, but not the normal way.

And then I found this thread:
https://www.67-72chevytrucks.com/vbo...d.php?t=695112

Post 15 Vette Vette is a treasure....

I had tried a new switch and that didn't fix my problem. So I thought! I took the new switch back out and put the old one in.

After reading this thread, I decided I would clean the paint off to make sure the switch was grounding and check with a meter to make sure it was grounded. It was. But still not wipers.

Dug up the new switch and reinstalled. Yay, I have wipers now!

Yep, good work! There are some good guys in here that know these trucks, Leon and Vettevet are a couple of them.
Until I made sure the switch was set in the pocket just right it wouldn't ground to the dash to get the wiper motor to run in wiper mode. Someone had already been in mine before so I couldn't tell exactly how the grounding spot was supposed to look, but there was a bare spot at the flat edge at the top of the hole that made the ground. It has been a long time since I've worked on anything like this, but it almost looks like when the switch hole was punched, the flat edge was slightly raised (extruded) to guarantee a good ground there. Someone else might know more about that.
As far as the wiper working when the washer button is depressed, I believe that ground we see in the schematic at the cluster connection is why it works when the button is held in.

[Jason Banks]

Originally Posted by MS66

Until I made sure the switch was set in the pocket just right it wouldn't ground to the dash to get the wiper motor to run in wiper mode. Someone had already been in mine before so I couldn't tell exactly how the grounding spot was supposed to look, but there was a bare spot at the flat edge at the top of the hole that made the ground. It has been a long time since I've worked on anything like this, but it almost looks like when the switch hole was punched, the flat edge was slightly raised (extruded) to guarantee a good ground there. Someone else might know more about that.
As far as the wiper working when the washer button is depressed, I believe that ground we see in the schematic at the cluster connection is why it works when the button is held in.

I really needed to clean that paint off good. My truck was a total repaint, I hadn't stripped the factory paint off the dash like I did the rest of the truck. Then it had Epoxy primer, 2k primer, base coat, 4 coats of clear.

Further exacerbating the problem was, my truck is 1968 and I changed to later style dash bezel and extended the wiper wires over to where the choke was, so the hole is not the same shape as the real wiper switch hole.

[MS66]

Originally Posted by Jason Banks

I really needed to clean that paint off good. My truck was a total repaint, I hadn't stripped the factory paint off the dash like I did the rest of the truck. Then it had Epoxy primer, 2k primer, base coat, 4 coats of clear.

Further exacerbating the problem was, my truck is 1968 and I changed to later style dash bezel and extended the wiper wires over to where the choke was, so the hole is not the same shape as the real wiper switch hole.