washer/wiper motor wiring

[turpentyne]

Another challenge on a 1973 C20 I just bought. I've got a non-working horn, and non-working windshield wipers.

First up, I'll tackle the windshield wiper. But I'm not sure where to start. I took a photo of what I've got. I can see a yellow wire and black wire attached down below, which seems to match a wiring diagram I found online, but I'm stumped from there. I do see 2 clipped wires (at bottom left of photo ) that are purple and red. I don't know what they go to. Maybe an after-market cruise control function that was added at some time in the past.

Any suggestions for what goes where on the wiring would be appreciated.

Here's the photo I took:

[BidEquation78]

I had similar problems with my 82'... spent all the money for new parts and it turns out the terminals just needed cleaned LOL! First id check all the connections and relays/fuses and go from there.