[BonzoHansen]

It’s a matter of finding what the circuits have in common, ignoring the possibility of sheer coincidence. I can’t think of anywhere else off the top of my head where the radio circuit + the wiper circuit might intersect. One might say the fusible link at the starter, but links are not intermittent (unless the wire is loose, but even then the jump in resistance would likely blow the link out in a short time), and often impact more, like the car running & starting. The ignition switch controls power to a lot of circuits and contacts can wear out. I had one that would give me weird intermittent issues. Those are hard to find. It is way easier if it just dies.

I need to find a good wiring diagram for that car and see how those circuits run. I’ll see what I have on the shelf. This is why everyone should buy manuals, LOL.