ELECTRIC Windshield wiper motor switch

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m3a1
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ELECTRIC Windshield wiper motor switch

Unread post by m3a1 » March 3rd, 2020, 2:05 pm

Ok, gang. On the matter of removing the little lever on the wiper motor switch so as to clean and inspect the contacts under the housing...how exactly is that little lever held on there? I see the beginnings of a tiny hole under all that paint. Am I looking at a pin in there, a tiny screw, or what?

Cheers,
TJ
Last edited by m3a1 on March 3rd, 2020, 3:18 pm, edited 1 time in total.

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Re: ELECTRIC Windshield wiper motor switch

Unread post by m3a1 » March 3rd, 2020, 3:17 pm

Ok, going to answer my own question now and in a bit, follow up with a series of photos so if you've been curious about what is going on inside your electric wiper motor switch this will be a great opportunity for you to get a peek.

As to the question of how the switch lever attaches to the switch's stud, it IS a pin and that pin goes through one side of the lever and through the shaft section.

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Re: ELECTRIC Windshield wiper motor switch

Unread post by m3a1 » March 3rd, 2020, 9:04 pm

So I thought maybe I would get into this, make a small repair and all would be well (such was not the case) and so, you will see that my initial efforts were made with the motor still mounted up to the windshield frame.

I began with removing the switch lever which turned out to be pinned in place. Since there was some kind of sealant or plug on the top of the pin, I pre-drilled that hole with a slightly larger bit so as to be able to see the pin. Eventually, I drilled out the pin which turned out to be 1/16" in diameter and it is inserted in a blind hole. It does not go all the way across the switch lever body. It could, if you wanted to reassemble it in that way and it certainly wouldn't hurt anything. My only suggestion would be to use a pin that remains just a little bit proud (taller) of the switch lever body. Having a bit sticking out might just help the next fellow who wants to get into the switch. It certainly wouldn't hurt anything.

The pin's only job is to keep the switch lever on the shaft. The shaft is round, with a flat spot machined into it; a very common design for rotary switches, so there is not need to worry about the lever not being able to adequately turn the shaft.

Now is also a good time to mention that, if you have a sloppy switch, you might try tightening the nut behind the switch lever just a nudge. This will draw the plate (inside the switch) closer to the detents in the chassis of the switch. I'll give you a look at how that works just a bit later in this post.

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In the next two photos there are several things I'd like to point out. First, the switch housing is soft, like pot metal. The screws that hold it in place are brass so all of this stuff is soft. Plus there is an O-ring on the circumference of the switch housing. Between the O-ring (and a little silicone grease) there will be a good water-resistant seal. Ergo, there is no reason to tighten these retaining screws down 'gorilla tight' upon reassembly.

Second, take note of the wavy spring steel washer hanging over the wires. This serves to put pressure against the internal plate.

Third, the wires are attached to the switch with a press fit much like all the other contacts in our wiring harnesses.

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I believe this is a reed switch that turns the wipers off at their stowed position. Would anyone care to confirm?

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It is directly in line with the power source.

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Here we have the inner plate, with contacts. Note that the locating pin at the six o'clock position in the plate and corresponding notch on the main housing. If, during reassembly, the switch housing will not seat fully against the main housing this pin is not properly aligned with the notch.

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To get inside the switch, gently pry back the three tabs. Just work them up and away a little bit at a time. Do two a bit more than the third and you will find the switch will open very nicely. Do not over work these tabs. Just move them enough to work the back off the switch. There is a spring in there but it doesn't exert a terrible amount of pressure so a bunch of stuff won't come flying out. Just gently work the back up and off and you're good to go.

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Obviously, this switch is in very good health and isn't the source of my troubles. The assembled contact plate is properly aligned by means of two tabs and two slots.

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Make note of its proper orientation upon disassembly. Here, we can also see the plate with the detents, to which the shaft is attached.

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The copper contact plate simply sits on the backing plate (not permanently affixed) and it is aligned with two tabs and two small raised areas that will indicate how it is oriented to the backing plate.

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And finally, another better view of the spring and the detents.

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Because I got no results from going through the switch (yes, I checked to ensure I had a good power supply in the first place) I thought that perhaps the mechanism might be frozen somewhere so I got inside the windshield frame. By golly, those wasps have been busy, but even all that wasn't sufficient to inhibit the mechanism as most of it was broken up into chunks and laying in the bottom of the windshield frame. This did mean I was going to have to get in there and clean up all that junk.. Which begs the question, what is in your windshield frame?

I will go over how best to remove the wiper arms in a later post.

Be gently persuasive in removing the outer panel. It has a rather unique gasket.

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Exposed some nice original paint along the way.

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And then there was the matter of removing that bloody awful little clip which was necessary for checking the free movement of the armature. Long story short, I managed to get it off.

Also note that removing the cover plate allows access to the two internal bolts that must be removed before the motor can be taken off the windshield frame.

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I did finally remove the motor in its entirely and found it to turn but it was frustratingly stiff. So, I think there will be more to do on it, if only to try to determine what the problem is.

Cheers,
TJ

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Re: ELECTRIC Windshield wiper motor switch

Unread post by rickf » March 3rd, 2020, 10:05 pm

I know we had talked about that reed switch as possibly being the park circuit switch but now I see it and it is not on a moving part so that is not it. If it look like it could possibly be a resetable breaker it is probably just that, a circuit breaker to cut power to the wipers if they are frozen to the windshield or otherwise restricted from moving. It will heat up and trip and reset as it cools down.
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Re: ELECTRIC Windshield wiper motor switch

Unread post by m3a1 » March 4th, 2020, 12:15 am

Ah, so do you suppose that black, button sized bit on the inner plate is a small coil that provides enough power to get the wipers back to their "parked" position?

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Re: ELECTRIC Windshield wiper motor switch

Unread post by Mark » March 4th, 2020, 12:42 am

On the older mutts with vacuum wipers, there was the manual hand operated lever to move the wiper blades in case you lost vacuum for some unknown reason.I know this has nothing to do with this post so maybe the watchdog will delete it? Aw, this was for GP!
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Re: ELECTRIC Windshield wiper motor switch

Unread post by rickf » March 4th, 2020, 9:26 am

That is a compression spring, not a clock spring. I would think that is just to keep pressure on the contacts to keep it all connected. Most wiper motors will have an extra wire which yours appears to have and when the switch is turned off the power is switched to that wire which reverses the motor and when the gear hit a certain spot it disconnects. There are many different versions of how this function works so it would be impossible to say what version you have. I think the bulb is nothing more than a thermal switch to protect the components in case the wipers are frozen to the windshield or buried in snow.
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone

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Re: ELECTRIC Windshield wiper motor switch

Unread post by m3a1 » March 4th, 2020, 1:16 pm

Out of an abundance of caution (and the acknowledgement that I am definitely not an electrical wizard) I ordered a new wiper motor kit. So, the gloves are off and I will be getting into this old one a bit more deeply because I would very much like to figure out just what has failed in this unit.. One minute it's working fine and the next minute....nothing.

Suffice to say that if one of our readers finds himself in my position, the switch section on an old unit could be tested, salvaged and set aside for later..

Cheers,
TJ

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Re: ELECTRIC Windshield wiper motor switch

Unread post by Lou » March 4th, 2020, 9:59 pm

The glass bulb is a thermal circuit breaker. It works like the old fashioned flasher for the turn signals. When too much current is drawn through it the bimetallic arms heat up and pull the contacts open. :wink:
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Re: ELECTRIC Windshield wiper motor switch

Unread post by m3a1 » March 4th, 2020, 10:36 pm

Okay, here we go. I took this thing apart without any regard to putting it back together again since I had no intent of making repairs. I think I found the culprit almost immediately. If I had only known, right?

Image

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Here are the brushes, which are located in the end cap of the motor (fastened with 5/16" bolts). If, after viewing this post you think you might want to get into your wiper motor and do a little preventative maintenance in this area, be forewarned, there is very little extra wiring at the end cap and so very little length with which to lift the cap off and get at this business. Doubly difficult to compress the brushes into their housings and then put it back on the armature. So, if you elect to try this, far better that you attempt to clean these points of contact with end cap still on the armature.

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The two large philips head screws hold the field windings in the housing.

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In order to remove the motor from the gearbox chassis you would have to desolder these two wires. Rick, I'm still of a mind that this little black gizmo is a coil, storing energy until the wipers are shut off. On the back side of this plate are two long spring steel contacts that rest against the large gear.

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I reckon that when the gear turns to the point where one of the contacts no longer rests against the the metal face, the current is interrupted, stopping the motor with the wipers are in their normal stowed position.

Image

Hope you guys found this interesting and perhaps even useful.

Cheers,
TJ

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Re: ELECTRIC Windshield wiper motor switch

Unread post by svramselaar » March 5th, 2020, 6:14 am

hi

from the fuse the power is on the switch and the copper plate trow the resistor
if you look at the plate ther is a opening in the outside
for low speed you put with the switch direct power to the motor trow the resistor
for high speed direckt to the motor whithout resistor
if you put the motor off it gets power from the plate till the opening cut the power and it stops
at different motors wen the opening cuts the power the motor go at both sides at the the ground to stops it direct then you see three spores at the plate



george

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Re: ELECTRIC Windshield wiper motor switch

Unread post by Fil Bonica » March 5th, 2020, 12:13 pm

Given all the energy expended here wouldnt it be better just to trade out the wiper motor assembly for a good used or NOS assembly?
Sell you a new one .
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Re: ELECTRIC Windshield wiper motor switch

Unread post by m3a1 » March 5th, 2020, 3:25 pm

svramselaar wrote:
March 5th, 2020, 6:14 am
hi

from the fuse the power is on the switch and the copper plate trow the resistor
if you look at the plate ther is a opening in the outside
for low speed you put with the switch direct power to the motor trow the resistor
for high speed direckt to the motor whithout resistor
if you put the motor off it gets power from the plate till the opening cut the power and it stops
at different motors wen the opening cuts the power the motor go at both sides at the the ground to stops it direct then you see three spores at the plate



george
Ok, George, that kinda makes sense to me....at least I was partly correct... I'm not sure how how power gets to the plate after it's turned off but I'm gonna trust you on it! :lol: As I said, I'm not an electrician by any stretch of the imagination..

Fil, yes, I did source a replacement. She'll be good as new in a couple of days. This exercise was merely an interesting way to pass the time and I thought everyone might want to have a little look.

Cheers,
TJ

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Re: ELECTRIC Windshield wiper motor switch

Unread post by m3a1 » March 5th, 2020, 3:29 pm

Also, when it's time to reassemble this whole thing I'll do a little piece on removing the wiper blade arms (which can pose problems depending upon how long they've been on there). I developed a little trick which made a huge difference (at least to me) which I will share with the group along with photos showing the process. Hoping to get this puppy back together in a few days. Still waiting for the new part...

Cheers,
TJ

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Re: ELECTRIC Windshield wiper motor switch

Unread post by Fil Bonica » March 5th, 2020, 4:04 pm

Your patience and attention to detail far exceeds mine.
My attitude in that instance is to
“Get ur Done!
Hats off to you.

Fil Bonica
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