Note this horn here:
As far as I can tell, it does absolutely nothing, and is probably a vestigal organ of some earlier alarm system. I shall remove it.
First, we note that the horn lead enters a closed box on the driver's side of the firewall. Undo four screws, and we can open the box, revealing the following bits and some astonishingly amateurish bodged wiring wrapped with electrician's tape:
On the left is the Motronic engine computer. There are three relays in the middle and a mystery module on the right. The car is full of mystery modules. The horn lead passes through the box, through the firewall, and into the interior. Yay! We opened the box for nothing!
Pull down a panel under the dash, and out spills an old alarm controller and a mess of wires:
Assorted wires have already been cut -- presumably to disable the old alarm system. A LED, mounted nowhere, is found at the end of a cut pair of wires. Out it goes! Here's another view of the wires:
By following the wiring, it appears there are not one, but two unused alarms lurking down here. One of them appears to be behind the driver's side footwell panel. I'll open it in a day or two. The old alarm deactivation key, mounted on the light switch, can be removed to reveal this lovely hole:
Good thing I found a replacement light switch on eBay, isn't it? It should arrive in a few days.
I had a heart-stopping moment. The power mirrors don't work, and I found a disconnected plug and socket amidst the wires that looked suspiciously like a reasonable suspect. I connected them and turned on the key. A few clicks came from the fuse and relay box on the passenger side of the firewall, the instrument cluster lit up like usual, and then it went blank! I turned off the key. Turned it on again, and the instrument cluster was completely dead. Oh no! I've killed it! Never, ever, ever plug a random plug 'A' into random socket 'B' just because it fits! Never again!
Heartbroken at having killed a bit of my poor car, I ran into the house and logged onto eBay in a desperate bid to find a replacement instrument cluster. Yay! Found one! Two minutes to go! Better bid thousands in case it goe- Oh, wait. It's for a different model, and doesn't have the same arrangement of display panels and whatnot. Damn! Misery!
Then it dawned on me to check the fuses. Sure enough, a fuse was burned out. I replaced it, and the instrument panel worked again. Heave vast sigh of relief, and don't touch the car again that day.
Here's the engine bay, in case you were wondering what it looked like:
I brought in the glovebox and washed it in the sink. Here it is drying on the dish rack:
The glovebox is now back in the vehicle, though one of the strap pins is missing. I won't purchase a new one until I've verified that it isn't rolling around the floor somewhere.
I pulled up the rear seat pad and retrieved the centre seat belt which had fallen between the seat back and the pad. I forgot to take a pic of it, but there is an enormous black mystery module under the passenger's side of the seat pad. What does it do?
Oh yeah... I tightened a loose fastener on the rear spoiler. That didn't cure the rattle. It seems the brake light lens on the spoiler fits rather poorly, and rattles when the boot is shut. Tomorrow, I'll stuff some putty in the gaps to tighten it up. Under further examination, it appears not to be a factory item but an aftermarket bit that was probably added shortly before or after purchase, perhaps by the dealership.
More later, or tomorrow.