That being said, I must state this disclaimer...
***I am not an electronics expert. I assume no responsibility or liability for any damage to your vehicle or other property for attempting this repair. This is a temporary fix, not a permanent repair. As always disconnect your battery before working on the electrical system***
First thing I want to show you is the pinout continuity test for the switch. I have an entire Adobe file with wiring diagrams and testing procedures for 77-82 Ford wiper systems if somebody wants to suggest a way to share I would gladly do so.
Looking at this the first thing I noticed that any time the wipers were on in low or high the terminals A-G-H had continuity, or were connected together. The only difference between speeds was which terminal C or E was connected to D. I looked at the base of my separated switch.
I noticed terminals A & H were always connected together with a 8 1/4 amp circuit breaker between the two terminals. when the switch was rotated to the low position terminals C&D connected and G&H connected. Turn the switch to high and D&E connected and G&H stayed connected. I was ready to mark my switch socket and wire a bypass.
I discovered Molex .093 male pin crimp terminals fit the female terminals in the Ford factory connecter. These are pretty common. I got mine from a 9 pin molex connecter kit from Radio Shack part #2740229. Napa and Car Quest should have them in their Weather Pack connector supplies. You might be able to raid some from connecters at the junk yards, if you go this route make sure the wire is at least 16ga. Here's a picture of the pin terminal.
I crimped the connecters on lengths of 16ga wire then soldered them. I pushed one into Ford connecter on the vehicle. I then slid a length of heat shrink tube over the wire and pin terminal until no metal was exposed. I repeated that for the remaining leads. Sorry I don't have pictures of that I ran out of light and the half of me hanging out from under the dash was soaked. Here's a very basic circuit diagram I made in MS Paint. I hope it makes sense.
The way I am running it terminal A connects to an ATC (blade style) fuse holder I have a 10 amp fuse in it now, but I am replacing it with an 8amp circuit breaker that fits the holder as soon as I receive it from O'reilly Auto. The wire exiting from the fuse holder connects to two wires, one plugs into terminal H, the other connects to one side of a toggle switch. The wire from terminal G connects to the other side of the toggle switch. That completes the power side of the wiring. The speed control side is as simple as you want it to be. Make a jumper and connect terminal C&D for low, or terminal D&E for high speed. I included a example of how to wire a SPDT switch to change speeds on the fly, if you have room to run a second switch. The only switch you have to turn off is the power circuit, you will not have park function, but at least you can use your wipers in an emergency while you're waiting on that replacement switch. You could also take 12volts from the terminal G side of your power toggle switch run it to a momentary on push button switch and then to that terminal marked with a "W" and your washer pump will spray.
Please be careful, don't eliminate the circuit protection. Use a circuit breaker of some sorts, no bigger than a 10amp. Be safe!
