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.

 

To complement your work, here are some part numbers that may prove helpful.

Your cover has a top center hole, which may be a superseded part of the following. To find out the models these numbers fit use the url of http://oemcats.com/oem-parts/xxxxxxxx.html where xxxxxxxx is the part number you want info about e.g. GM 22137719 Cover, genuine OEM part lists Caprice 1991...1996 and Roadmaster sedan/Estate wagon 1993...1996

22137719
22139166
22154753

All three are unobtainium in NOS, which requires raiding a junkyard, emailing Fred Kiehl for a used unit, or going NOS for the cover and circuit board, and transplanting your cam.

22137809
22101357
22063284

There are four on ebay now (2/9/21) from $20-$40, item numbers are:

203090312470
183375155102
372969360030
142821968423

 

This rocks!

Why is this not a sticky?

 

Matt Smith - again, great work!

Can you clarify something for me? In your ladder diagram you have 3 relays, Park, K1 and K2 (coils and contacts...although Park is missing the NC). K1/K2 are the only relays on the board and the manual has park relay and timing relay. K1 you list as INT on the ladder diagram...so I'm guessing that is part of the "timing" relay. K2 has no listing but listed in your notes as wash pump related.

 

Hi dubulup, let me give it a shot...

Yep - 3 relays...

Park = only has one set of contacts. It's a "relay" but doesn't function like K1 and K2. The contacts are held open by the mechanical lever when parked, but when the coil is energized it pulls the lever off the contacts and allows them to close which starts the process of coming out of park This is the one that there is a video of how it works.

K1 is a traditional SPDT relay (big black rectangle on the circuit board). The N/C terminal is not connected to anything. The K1 coil is powered from terminal C1-B through diode CR5 in any stalk position except "Off" and grounded by 3 different paths to energize the relay, which closes the contacts and supplies power to the Park Relay contacts.
1) Q1 Transistor which controls the pulse/delay time after the sweep cam stops the wipers at the end of sweep
2) Q4 Transistor which controls how long the wipers run after a wash command
3) The end of sweep cam (the plastic one) which opens the K1 Coil circuit when the wipers hit end of sweep position (not parked)

K2 is identical to K1 except that its coil is only grounded when Pin F gets a straight shot of battery voltage from the stalk when the wash button is pushed and Q4 Transistor connects it to ground, closing the contacts and powering C1-D to power the wash pump.

The "Solid State Timer Relay" is actually all the discrete components (diodes, resistors, capacitors, transistors) shown in the ladder diagram. It is not a single part/assembly in and of itself.

The INT nomenclature was to denote "intermittent" (or pulse, or delay ) as that is the relay which controls that functionality.

I hope that helps explain it a bit better, if not reply back and I'll try and clarify.

 

Ah, thanks for the detailed response, I’ll have to digest all that when I return to my desk/bench in morning…much appreciated!

In short if I understand, the park relay is the park switch…I was reading/watching as if they were separate parts. The manual was confusing me as it looks like it [park relay] is drawn on the “board” but now that you set me straight, the relay / arm drawn in the manual makes perfect sense after watching your video.

 

Figured that I'd circle back to this thread and add the below schematic which adds a bit more detail to the original factory schematic and compliments the hand drawn "ladder diagram" above.