Turbaxel!
Thank you for this post!
I´ve done exactly (except for the computer cable!) what you did mentioned about the looking for and testing for the problem

!
I´ve used my Fluke industrial DMM for this with some extra cables from another car just for the reason not to risk to use cables with too small area during the testing procedure with the power on. The ohm test doesn´t need that area, that´s right!
For the moment I have the electric wiring to the left on the floor extracted from the door and back to a "working condition" (the window stopped in the most down position...) and I and our doughter are quite sick in the flu since almost 10 days, BUT

when back in the shoes I´ll replace EVERY cable that indicates ANY signs of "age" for a brand new one with as many single copper leads - a stranded one seems to be the correct word after a search in Google, as possible.
For the moment the LEDs for 2 out of 4 switches at the doors are dead = no red light is coming from the switshes.
I´ve spent hours to find an electric wiring diagram for the year 1990/1991 as my VAG AUDI original thick (!) manual from North America (Ebay

) is for my 1985 100 2.2E.
I´ve found some last night that I will check out against the colours of the cables.
+++
If a german owner are able to help me with a high resolution picture by a camera from a manual of this and all the relays and their numbers on the top and what they are for, I would appreciate that offer and his time very much!
+++
Why I ask for a german member OR a swede, thank you, is that our cars
meant for these two markets should be almost the same, right..?
Kindest regards & with thank´s to all of U nice members out there!
Tony