Ok, this one takes awhile to develop, but (I think) there's a good payoff at the end. Bear with me here...
So today the Milano's blower fan, radio, and rear windows, which had been quite flakey in the ol' function department, decided to pack up for good. Since they were all going at once, and since the radio was involved, I figured something that @#%#@ stoner installer did was at fault. After all, I'd already found two, count them two, bare hot wires floating around back there.
So, pop out the radio and what do we have? Well, things are dead. This means power is not flowing. I find the hot wire and after some judicious probing with the ol' test light, sure enough, it's still hot. That leaves the ground.
Now, Alfas are legendary for bad grounds anyway. Lights do not make a car go fast, so Italians feel this is a great place to experiment with cheap geegaws. Which seldom work. So, since the radio's involved, let's go find the radio's ground wire. Ah, there it is, black like all the rest of the ground wires in the world.
Follow this for a few inches and I find a wire cap that joins three black wires together. One of these three black wires comes out of an original wire harness plug. In fact, it's the only wire still there, since the @$##@ stoner saw fit to snip all the rest, including the one that powered the clock. But that's a different story.
Previous experiments had revealed this ground wire also, somehow, was the ground for the fan and the rear windows. Ah-ha!. So, it's a simple matter of a spool of black wire, a few connectors, and a convenient bolt and voila, a new, known-good ground. Stuff the other end of this into the wire nut and sure enough, everything starts working again. Problem found.
Now, first to determine which end of the existing ground wire is coming from the fan and windows, and which end is heading toward some other mysterious point on the chassis. Investigation reveals it comes down into the plug, through the socket, and out the other side where the wire nut is. Ok, easy enough. One of those three wires must eventually lead to the firewall.
Splice the one that comes out of the plug to our first new "known good" ground. Make another wire to ground the radio, who's ground is easy to spot since it comes out of the ass of the radio itself, and ends in that wire nut I just snipped off.
Now, to test. Fan comes on, fan goes off. Windows go up, windows go down. Radio turns on, radio turns off. Satellite radio...
Satellite radio sits there "finding signal." F---.
Ok. The problem usually lies with something I've been tinkering with. Which is these grounds. So, I go to the passenger footwell, who's carpet under which the @#%# stoner hid the Sirius components, and find its power source. Test light shows it's got power. So I start following the ground wire around this, through that, past the other thing, right to...
The other ground wire under the nut.
This is the "WTF?!?" moment. So, the third wire did not in fact go off to become one with the firewall. It seems to have gone to the Sirius box.
Now, I'm (obviously) no electrical genius, but I'm pretty sure this means all three subsystems were relying on each other for a ground.
Suddenly, I'm not surprised it failed. I'm surprised it ever worked at all.
I ran out of time and connectors before I could get the Sirius going. It's just possible I go the wires crossed and didn't in fact trace the ground properly. But still...