Rear Windshield Wiper Mystery Solved

Jtraskell

New member
I THINK I solved the mystery as to why the WW does not go all the way across the rear windshield, but I never said I fixed it! That is why I am posting. If I am correct as to why, maybe some of you engineering geniuses out there can edify us as to how to correct it, if possible!

Alright, took off the rear spoiler. Pretty easy, take off the nut (10mm) holding on the rear windshield wiper arm and blade to the wiper post. Then, just to be safe, take off that little rubber shield after the arm comes off. It just lifts off the post. Make sure the wiper arm and blade was in the full retracted position when you remove it. I will explain why later.

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Then take off the 4 rubber plugs just on the inside top of the rear door. Inside, 4- 10MM short bolts.

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From there, just pull out carefully. There are also 3 plastic guide pins towards the inside top of the spoiler. They do not clip in, but be careful not break them pulling the spoiler off or putting it back on with too much of an angle. As you are holding the spoiler in one hand, disconnect the electrical plug that goes to the wiper motor. There is one more wire going into the door, I did not figure out where it went too or how to disconnect it , but once I disconnected the wiper motor electrical connection, I had enough slack to just rest the spoiler on top of the truck.

Ok, now you can see the wiper motor. Remember this. When you took the wiper blade off, the blade was in the full UP position. (Tucked under the spoiler). Therefore, the gears inside the motor, if removed, should be placed in the same position as you will find them right now just to be safe. It may not really matter the way this is designed, but just in case, keep this in mind.

Remove the wiper motor. 3- 10 mm bolts. No need to take them completely off, just unloosen enough to come off the back plate. The bolts will stay in the rubber bushings just fine.

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Now, take the motor to a work bench area and remove the 6 screws on the back. Note: Rest the motor somehow where there is no pressure on the wiper blade post before you pull off the back plate. If you don’t, the weight of the unit will push on the post, pushing up on all the gears and when you open the plate, all the gears will pop out before you have a chance to look at how they were placed in the unit!

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This is what you see when you open the back plate. See the screw sticking out of the top left of the unit? It has a lock nut on it. I thought that might be some sort of adjustment screw, but it would not turn all. Yes, I loosened the lock nut first. Not sure what this screw is really for, but as you will see, I do not think it has anything to do with adjusting the sweep of the WW.

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The large white plastic gear on the right seems to be the Key. If you lift up on the gear unit on the left, it allows easy removal. Note, this is where you need to keep a good mental note or photo, prior to removing any gears so you can put them back in the same place when rebuilding.

After removing the gear, you can see three electrical contacts. On the bottom side of that white gear, one can see 3 metal strips embossed onto the plastic. I am thinking the 2 strips closest to the center are the contacts which control the “sweep” of the WW. This because they are of equal distance in length and plane on the gear. I think the third metal strip is the one which controls the return of the WW up to the retracted position. That is just a guess on my part, but it makes sense in a twisted sort of way……

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Ok, assuming I am correct and the sweep is controlled by the 2 equal metal strips closest to the center of the gear, then lengthening the contact points on either one side or both sides should cause the WW to continue in the sweeping motion for as long as contact is made. So maybe 1/8th or ¼ of an inch longer metal embossment would do the trick. The problem is how does one add metal contact to these metal strips? A little grinding then filling with solder? Metal tape? Any suggestions? The best solution would be to contact the manufacturer and have them replace the gear……
 
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The sweep is regulated by the number of teeth on the "gear" attached to the white plastic wheel.

Where did all the pictures go?
 
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I'm gonna go with "senses when wiper hits obstruction".

Something is not making sense Mike. I agree, the gear you are referring to does cause the sweep, but I am not sure it "controls" the sweep. Here is why. When you turn on the WW, the wiper blade drops down and sweeps, lets say for the sake of argument, 24 inches from side to side. Let's say that sweep uses 90% of the gear span you are referring too. But when you turn off the wiper, the blade goes past the stopping point (at least on the passenger side), then tucks itself lets say 6 inches higher to hide under the spoiler. That being said, there should be enough gear span on your gear, to allow the wiper to sweep at a longer arch during the normal sweeping mode since there is enough gearing to drive the wiper up into the retract mode. Am I making sense or?
 
So let's presume the two contacts provide feedback to the motor control; it hits the end of them and the motor reverses the sweep. The computer looks to see where the switch is positioned and either continues the pattern selected or send the wiper home. Either way, the strips are not going to give you any more arc because if the "gear" goes past it's number of teeth, the wiper is no longer under any control and will just hang down. You have discovered why it's such a shallow arc, but from the pictures (that I can no longer see) it's clear that there is no way to "fix" it. Unless you want to fab a whole new unit.
 
OOOh! OOOOh! OOOOhhh! (remember Horseshack?)

I wanna see! Fix them pics OP! All I see are tiny x's...:cry:
 
OOOh! OOOOh! OOOOhhh! (remember Horseshack?)

I wanna see! Fix them pics OP! All I see are tiny x's...:cry:

That is weird, I am seeing the photos just fine, just like when I ori posted them. Can't fix what I can't see what's broke.

Mike, I agree with your last post but I guess that is my point. There ARE enough teeth in that gear to go at least 6 inches farther then the normal sweep, at least on the passenger side, because the retraction of the blade has to go that far to tuck under the spoiler. And the only way to do that, is using that gear which operates the post where the wiper is attached. We would only need say 3 inches more per side to make a "full window" sweep. Maybe that can be done by extending the electrical contacts on the bottom of the white gear, maybe not. All these measurements are just examples, I am not sure of the actual distances.
 
That is weird, I am seeing the photos just fine, just like when I ori posted them. Can't fix what I can't see what's broke.
for some reason, they are no longer showing up at attachments.
Mike, I agree with your last post but I guess that is my point. There ARE enough teeth in that gear to go at least 6 inches farther then the normal sweep, at least on the passenger side, because the retraction of the blade has to go that far to tuck under the spoiler. And the only way to do that, is using that gear which operates the post where the wiper is attached. We would only need say 3 inches more per side to make a "full window" sweep. Maybe that can be done by extending the electrical contacts on the bottom of the white gear, maybe not. All these measurements are just examples, I am not sure of the actual distances.

I don't think you are following the physics of the arc correctly. The absolute limit of travel is where it ends, not where it begins. The number of teeth on the "gear" in question will turn the wiper out to that mark, but if it goes any further, the teeth will no longer mesh with the opposing gear and the blade will just droop down.
 
For some reason, I can't see the pictures either. I'm flying blind, but I'll take a shot at an explanation. I disassembled a wiper motor on a Camaro many years ago. The motor rotated in the same direction until polarity was reversed. I think this is what is happening at the end of the arc. When power is first applied, the wiper motor starts moving. Once it travels for a short distance, the contacts engage and provide continuous power for the entire stroke. This is why, even though you turn power off at the switch in mid arc, the wiper blade continues to move. Once the wiper gets to the stop position, the contacts switch, and this reverses polarity to the motor. This causes it to immediately move in the opposite direction. If power is still applied at the end of the cycle, the motor will reverse and repeat. If power is not present, the wiper will automatically move to the park position. The key is knowing where the blade is located, and this tells the motor when to reverse direction. This might not be the explanation, but for those that can see the pictures, let me know whether this makes sense.
 
for some reason, they are no longer showing up at attachments.


I don't think you are following the physics of the arc correctly. The absolute limit of travel is where it ends, not where it begins. The number of teeth on the "gear" in question will turn the wiper out to that mark, but if it goes any further, the teeth will no longer mesh with the opposing gear and the blade will just droop down.

I will fix the photos if somebody tells me what to do? I know it is weird, but I am seeing the photos just fine here. I did not do anything to cause the photos to go blank. Maybe the website itself did it? Here is the link to the three most important photos

Mike, you could be right. And I do understand the end of an Arc. But I do not think the beginning of this arc starts at either end of the gear you are talking about. I think it starts in the center. The gear is attached to a cam. The white gear spins in the same direction all the time (I think) causing the cam to move in one direction (forward if you will) as the white gear spins, until it spins past center, then it causes the cam to move in the other direction, causing the gear to go back wards.

I think I just answered my own question. If I am right and the sweep is controlled by the spin of the white gear in one direction, which moves the came, causing the gear you pointed out to move forward and back wards. No, it wil NEVER go past the last teeth on the gear (if it gets that far in the first place) but one could never make it go farther unless one changes the position of the cam on the white gear. Causing the leverage of the cam to go farther forward and back.
 

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I am going to correct myself a bit here. The arc does not start in the center, it would be slightly off center, enough for the gear to back and forth a certain distance when the white gear is traveling in the same direction, but when it the white gear goes in the other direction, for a short time, it causes to gear to travel a bit further, hence the ability of the blade to retract under the spoiler. Well, it's a good guess anyways. Thanks again all for the critical thinking lesson! (I may have flunked, but it was fun)
 
Maybe the rear wiper design is different but when dealing with almost any front wiper motor, the wheel completely goes full circle. It's the linkage that makes the wiper go the other direction. Polarity does not change in the motor. This would be very hard on the motor. This is going to be hard to describe in words, but here goes nothing...

Imagine your pedal on a bike. Your foot moves forward from 12-6. Then it moves backwards from 6-12. If your knee was the wiper, the only motion it sees is up and down. That is when the wiper goes backwards.

I imagine the contacts you see are for when the motor needs to stop and where it needs to "park" the wiper blade.
 
I think we've settled the question of "how" and yet we'll never settle the question of "why", as in 'why in the hell didn't they design it to cover 180 degrees of window in the first place?'
 
Maybe the rear wiper design is different but when dealing with almost any front wiper motor, the wheel completely goes full circle. It's the linkage that makes the wiper go the other direction. Polarity does not change in the motor. This would be very hard on the motor. This is going to be hard to describe in words, but here goes nothing...

Imagine your pedal on a bike. Your foot moves forward from 12-6. Then it moves backwards from 6-12. If your knee was the wiper, the only motion it sees is up and down. That is when the wiper goes backwards.

I imagine the contacts you see are for when the motor needs to stop and where it needs to "park" the wiper blade.

I think you, willie655 and I are saying the same thing in 3 completely different ways! And Seattlemike summed it up perfectly. It is almost like this wiper unit was originally designed for a smaller rear window....Highlander maybe?

That being said, no way for us to mod this unit. Need a different white gear with the cam in a different position along with a different drive gear with a few more teeth. In order for that to happen, probably need a "larger white gear", and for that to happen, need a larger case for the whole gearing system. If a larger case, I do not think it would fit under the spoiler as it sits now without some additional mods.

Anybody have any friends in a Toyota parts department that can do some research?

Again, thanks for your input guys. Be Safe.
 
I think you, willie655 and I are saying the same thing in 3 completely different ways! And Seattlemike summed it up perfectly. It is almost like this wiper unit was originally designed for a smaller rear window....Highlander maybe?

That being said, no way for us to mod this unit. Need a different white gear with the cam in a different position along with a different drive gear with a few more teeth. In order for that to happen, probably need a "larger white gear", and for that to happen, need a larger case for the whole gearing system. If a larger case, I do not think it would fit under the spoiler as it sits now without some additional mods.

Anybody have any friends in a Toyota parts department that can do some research?

Again, thanks for your input guys. Be Safe.

Good job! Speaking from experience though - ANYTHING can be modded if you have enough to spend!
 
Good job! Speaking from experience though - ANYTHING can be modded if you have enough to spend!

Although I agree to an extent and money is not really an issue, solving the problem is more important to me. I know that sounds a bit weird, but as good as you guy's are at solving issues, I think you will agree. It is the challenge or the ride, more then the destination, that makes the trip worth while. Ok, I will get off the soap box now......be safe.
 
Although I agree to an extent and money is not really an issue, solving the problem is more important to me. I know that sounds a bit weird, but as good as you guy's are at solving issues, I think you will agree. It is the challenge or the ride, more then the destination, that makes the trip worth while. Ok, I will get off the soap box now......be safe.

There comes a time in any project's life when you have to ask yourself "Is it worth it?" No matter if it is time or money that is involved. Sometimes the end does not justify the means.
 
Even with a mod, I'm not sure it could go to much further. If you look under the wing, you can see where it is notched out to fit the wiper blade. On the left side of the notch, it is angled. That angle matches the max angle of the wiper blade.

Even if you put in new gears to make it go further, it would hit the underside of the wing. Not that you couldn't probably trim all that out. It just seems like a lot of work with little gain.
 

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