Back to the other side, where I reversed & re-scavenged the whole wiring harness, and moved it over to the other side. Which was entertaining, as the way the wiring was laying, there wasn't enough slack to really do it. So, relentless car-tinkerer that I am, I pulled the whole thing back into the engine, rearranged it, replaced the wonky piece, and put the whole thing back together. Then I tested it, and it worked, and all was very happy (except that I then had to replace one of the headlight bulbs which had apparently burnt out. Today or tomorrow, I'll replace both of them with brand new ones). And we take the car for reinspection on Monday! Hurray!!!
Meanwhile, we're going to take a stealth (since it's not technically legal 'till the reinspection) trip to IKEA to buy some much-needed bookshelves this weekend. It'll make a big dent in the spring cleaning!