Hi,

I don’t know anything about these cars but you said you were sitting in a steady rain and operating the car.
You probably haven’t done that very often unless you relax that way as these vehicles have comfortable seats!
That has to be a big clue as the whole affair is not normal for now an aging car.

You might have water leaking in around the windshield or while you were running the wipers, water came in on one of the wiper arms shafts! A somewhat common issue of aging for the 240’s rubber grommets.

You see why I want to go with a wiper arm leakages.
Since I was crossed with reading about those being programmed on Volvos, that makes it scary for me!
I suggest you look there an any place above the computers.
Follow the wiring from any possible entry point and look for spots with no dust laying about!
Check any harness connectors. The smell probably came from one of those and should have discoloration stains.

Sure seems like a whole lot of codes for one memory bank. That technology sure has changed since the early nineties 240 cars that I have!

I have no idea what all of those are but it appears it hasn’t been cleared in a long time and you had a smorgasbord of them to digest!

A check engine light was originally designed for the purposes of emission errors indications.
You can lots of things wrong with these newest cars that never trips for the engine light.

These systems are like a woven reed basket, that can look intact with strands running everywhere, but the strength of basket depends on all the strands being routed correctly.
Water can play havoc with these low voltage and current sensing circuits. With them coming on at the same time when they shouldn’t and overheats neighboring wires to a ground circuit.
The dimming cluster lights says power was being diverted.

Good luck looking for signs of a gremlin’s trails!

Phil