2003 Pontiac Montana, wipers frozen in snow, idiot (me) left them on, thinking they'd "break free".
Wipers now park in a vertical position. Doesn't affect the operation otherwise. Thinking this is simply a "re-align the wipers on the crank" thing, adjusted them as per manuals -- put them in pulse mode, wait until they park, then pull the motor crank and realign it. Nope -- when the park after a pulse, they're fine. When they're off, they're vertical.
Now I see that the motor crank has a switch on it, and a cam, and a slot and pin, and a spring all around it. Basically, like most things in cars, is another "simple" thing that has had years of thought put into it. Probably to try to survive abuse by idiots like myself, and to recover from most things that would down the Space Shuttle.
Can this cam mechanism be "reset" or recovered in some way? Is this a designed "fail-soft" behavior? What does all this crap in the cam do? I'm really curious.
What has probably happened is that the cam or gear responsible for tripping the "I'm parked" switch has been forcefully wrenched from its proper position on its shaft. It is very unlikely you can "fix" this because the gear/cam usually shatters (where it counts...not necessarily where you can see it).
But...
If you want to try... find the switch contacts, disassemble the gear/cam from the rest of the machinery. Consider filling the broken cavity into which the shaft used to fit with epoxy (2-part, slow dry) and then force the gear/cam back onto the shaft but now in the correct position. Don't forget to wash the gear/cam in several changes of solvent to remove all the lubricants that may be floating around in the cavity. Let the epoxy dry AT LEAST 48 hours before touching it.
The REAL solution is to visit a "recyclling" yard and get a wiper motor that works...or a dealer and buy a new one (possibly more expensive than buying another vehicle of the same vintage.)
Well, folks, here's a strange part. I have the crank cam assembly in my hand now, and I'm looking at what appears to be the electrical contact part, and nothing seems to be broken. What I'm looking at is a main crank consisting of a flat piece with the knob at one end (for the wiper arm that's under the hood, which extends to the other wiper), sandwiched between a cam on one side (with a notch that a spring loaded pin pops into when the cam rotates and locks), and another sort of cam on the other side with a slot in it. This last flat cam has the electrical contact piece on it, and is attached to that center, main flat crank piece against a tiny, slinky-sort of spring like a string wrapped around the separating disk.
All that complication being said, it SEEMS to me like this assembly is meant to allow the crank to move around separately when the wipers are stuck somehow, so the motor doesn't labor too much and burn out. Extra stress on one of the wiper arms (the rods under the hood, that is, not the blades above) causes that pin to be pulled out of the slot, and the cam on the top to turn free. I assume the spring is meant to exert friction to prevent the pin and cam from rotating in normal, non-stuck operation.
Bottom line -- it LOOKS like whatever has happened, the cam is back in a "normal" position (pin's back in the slot, cam's rotated back to where it was), and there's no damage. I just don't see how these three pieces of flat metal are in anything other than normal relative positions. If they're not, of course, I'd be able to rotate whatever it is back to normal.
I've got a FEELING that this clever mechanism is intended to absorb that abuse and allow a mechanic (or the driver) to simply force the mechanism back into a "normal" orientation.
This has me MUCHO INTRIGUED. And if it's not so, I just don't see the reason for all this monkey-motion hardware. If it IS so, wow. VERRRY clever. And, considering how much stress wipers can be under in various weather conditions, quite reasonable (especially considering that wipers are a major, often ignored, critical safety feature).
All we need is a GM engineer to spill the beans :-)
I'm really curious about this -- is this a common occurrence? And how the heck does this all work? (as you can see, I don't just want to fix it, I want to know more about it). There's a sensor/switch on the cam and plate that I can see. I assume, then, that there's another switch inside the motor, and that the motor itself has gears (which is what you're saying).
Also, pardon my ignorance, but what's "WBMA" mean?
Generally, one needs to disassemble the motor, IF it is serviceable and the gears have not been damaged, then realign the gears. If not, you will need to replace the motor. The cam simply moves the wiper arms from the 'park' position to the 'run' position, and vis versa, when turned to the 'On/Off' or 'Interval/Off' position.
Did you adjust the wipers at their connection to the shafts or adjust the crank where it attaches to the motor's shaft?
The motor will park at the same position relative to its gearbox output shaft. If the primary crank at this pont slips, adjusting the wipers on their shafts won't help.
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