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Discussion Starter #1
Welcome!

For my Roadmaster project I've had to dig into the wiper circuit design and theory of operation quite a bit. I wasn't able to find this info online and the Factory Service Manual, while good, left me wanting more detail, so I decided to dive in.

Below is the standard unit from most all B-Bodies as far as I know




Removing the black cover reveals a circuit board, cam, park relay and some of the gear train




If you remove the end of sweep cam, it looks like this underneath. It's hard to remove the clip without breaking the stud which kind of renders the whole cover assembly useless, so here is a picture so you don't have to break it :)


Once the cam is off, you can remove the circuit board




This is the schematic that you get from one of the online service manuals which is more/less the same as the Factory Service Manual (but easier to read in my opinion).


Here's the Factory version for comparison


The boxes in the above schematics that say "Solid State Relay" and "Park Relay" along with the text "End of Sweep Input" have a lot of little details in them that are not revealed in the above schematics. I created my own version of the schematics in a form kind of like a ladder diagram. I don't have access to a schematic drawing program so this is the best I could do with what I had. I'll update this someday if I get a software package to do so (Visio is my preferred tool for this kind of thing). The below is just the lower box that represents the wiper motor assembly only - it does not include the wiper stalk or anything inside the car


The park switch is a bit unique in it's operation. I took a video of it rather than trying to type out a dissertation of how it works...


More to come...
 

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Discussion Starter #2
The above is a good start, but my goal was for the below document to tie it all together in each of it's individual states so as I "Fix Until Broke" to make it work the way I want it to, I didn't have to go re-learn how each circuit functioned and how inter-connected they were with each other.

I'm sure there are a few mistakes in all of this - If you find one, please let me know so I can fix it!

1996 Roadmaster Wiper Circuit Theory of Operation - Rev 1.0

Here are a few pictures of the park relay in various states. I'll try to describe them as best as I can...

First are the contacts shown in the schematic that go to C1-A
If you look in the small hole just right of the "C" terminal, you'll see a set of open contacts. These are only open when the Park Relay is de-energized AND the mechanism is at the end of the sweep. Hopefully the video in the above post shows this better than I'm able to describe it :).


As soon as you energize the park relay, the solenoid pulls the arm and allows the contacts to close (shown below) which powers the low speed motor


Here's the coil side of the relay



I'm sure I'll dig into the mechanical side of these as well (the wipers in my 96 Hearse don't work mechanically) - I'll post up whatever I learn about that side of things as well.

Questions, comments, suggestions are welcome. Hopefully this is helpful to the community.
 
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