redpoint5

I'm a nerd so I will explain a problem I have found in detail and the solution I intend to impliment to solve this problem. Any advice is appreciated.

After sitting for a very short while, my truck windshield wipers rapidly loose the ability to efficiently remove water from the windshield. My observation is that when you turn off the wipers, the blades stop in the downward stroke causing the rubber blade to remain in an upward angle. After sitting like this they tend to harden to that position so that when you go to wipe again, they don't bend downward and instead chatter across the windshield.

My Subaru wipers do not stop at the end of the bottom stroke. Instead they travel just a fraction of an inch upward before turning off. This way the rubber is fixed in the proper direction for when you engage the wipers again.

My solution: Add a capacitor across the wiper motor. When the switch opens and removes power to the motor, the capacitor will have a small amount of power left that will cause the blades to travel slightly upwards before stopping.

Does this sound like a reasonable solution? What farad capacity would you think I need to move the motor for another fraction of a second?

It's funny what I think about when I'm bored at work.

wannadiesel

If your capacitor causes the wipers to move enough for the motor to come off the park switch, the wipers will just cycle again.

Sidewinder

The wipers on my truck do this already. They change direction and move up the windshield a couple of inches before they stop. It really bugs me- I want them to stop at the bottom.

Maybe you can adjust the park switch so yours do the same. Or you can trade me wiper motors.

paco72

this quote is absolutely correct, in fact it is profound! amazed at the quick thinking and knowledge on this site. being serious not trying to be funny.

redpoint5

I have taken this into consideration. As it is now, I flick my wipers on and off quickly just to get them to move up a tiny bit. The trick would be to get a capacitor that moves it enough without going too far. I haven't actually looked at where the park switch is, but I wonder if it would be easier to modify the switch instead?

SolarExpress

Have you thought about removing the wiper arms and rotating them one notch upwards? If you pull the arms off, you will notice there are quite a few splines on the shaft. Just dont move it to far or you will end up "wiping" the A-pillar.

TonyB

Rotating the arm one notch up only moves the arm...rotation (degrees) remains the same.

VW, at least the '06 models do this. Not sure how, though. Probably using the chassis computer (door locks, etc.).

If you do use a cap, be sure to protect the switch with a diode, so the switch does not create a spark discharge & damage the switch.

redpoint5

Good point TonyB. I had not taked that into consideration. Still, this could end up being a cheap remedy for something that annoys me in the rainy state of Oregon.

TonyB

So, in the interest of simplicity, have you tried silicone wiper blades?

redpoint5

HAHA...no. I don't know much about wiper technology so I just bought the cheapest ones I could on sale. I might give them a try, but I'm sure most blades would last longer if they were stopped in the upstroke. Mine are working well so far because I am maticulous about where I let them rest.

FMB

So, let me get this straight.... currently, your blade stops on the down stroke, leaving the wiper bent upward and it hardens in this position. Your belief is because of this, it chatters as it goes up the window and wipes on the down stroke.

Further, you wish to keep the wiper motor sequence going just long enough so the wiper begins its trip back up, enough to change the wiper bend but not enough to cycle another trip up and back. You believe this may assist in the capabilities of the wiper on a wet windshield and reduce chatter.

It seems to me, according to the "Redpoint5 Harden Theory", the blade would be bent downward and would wipe on the upstroke and chatter on the downstroke. Hmmmmm... Chatter on the upstroke or the downstroke; which would be better?

SoTexRattler

I'll have to go dig out the manual to confirm if the wiper motor down-stop switch simply opens, allowing a simple coast-to-stop. The reason I'm doubtful is, auto mfr's now tend to use a dynamic braking ckt to get DC motors to stop RIGHT NOW and not coast a bit... Our truck's window toggle switches have that braking method inherent in their design... The window motor is shorted on switch release. Without it they REALLY coast !
If this is the case for the wiper motor, adding a cap won't do any good. It'll just make more spark when the braking contact makes. But I'll see what the book says...

However,whenever my wipers start chattering, they're toast!.. Time for some nice soft new ones... This spring when I replaced mine, I wanted some nice Silicone wipers but NAPA & OhReally's didn't have any to fit a Ram .


K.

redpoint5

FMB- I follow that logic, but for some reason unknown to me the blades just work better when they efficiently remove water on the upstroke and then return on the down. Perhaps this has something to do with the window having moisture on the upstroke and none on the down? My blades do not chatter on the down stroke even though they are bent the wrong way and the windshield is dry. Where is Bill Nye or the Myth Busters when you need them...

SoTexRattler- I had no idea some wiper motors were designed with the electric brake. This would indeed defeat the purpose of adding a capacitor. Because they are cheap, I will most likely just try it out and report back if it acomplishes what I want.

SoTexRattler

OK, I looked into it and it does seem to appear it uses dynamic braking when the wipers reach the down position. I say "appears" since the two main schematics in the '97 manual don't show anything that's within the Intermittent Wiper Control Module (Schematics 8W-53-2 and 8W-53-3)... BUT, the -3 schematic shows the wiper motor schematic clearly having an SPDT switch driven by the position cam labeled "UP" and "DOWN". If it is "Up", it provides for continued power to the motor (thru V6). And if it is "down" in it's "parked" position, the "DOWN" grounded contact is made.. Curiously, on the -2 schematic, it doesn't even show the crucial "up/down" switch common wire (V5) coming to of the motor module . But it would appear that when the multifunction control switch is moved to "OFF" or "DELAY" the "Wiper Switch Mode Sense line"(V5)is grounded when the wipers reach bottom... Therefore, as soon as the "UP/DOWN" spdt cam switch trips, V5 shorts the hot side of the motor bringing it to a VERY swift stop. Granted, this is probably accomplished through transistor switching within the Mystery Module, but all the other evidence is there to provide for dynamic braking.

The upshot of all this is... If the wipers are ending up warping the wrong direction at rest, blame the adjustment of the little SPDT cam switch within the wiper motor module itself...

K.

SolarExpress

I dont see how this is. I have removed the arms on my Dakota on numerous occasions and did not install them exactly in the same position. I had the wiper going completly off of the A-pillar on the driver side blade before. Took the blade off and dropped it a couple of notches and it went just to the a-pillar and stopped just above the sill. Sounds like someone here just doesnt want to buy new blades. Try cleaning them if you want to try and get a couple more miles out of them. Otherwise, worn blades chatter.

As a side note, I still have my factory blades (truck was on the lot in 2/05 I purchased on 9/05. Currently with 30K miles). When these decide to die, I think I just might have to pay the premium for the blades from the dealer. I never get more than 3-4 months from aftermarket blades.