RL correctly said the speaker wires don't go into the fan relay control unit. Once I followed the wire bundle, it went into the diagnostic port. The port and unit were jambed close together and I didn't follow the wire bundle carefully enough.
The FRCU has its own wires but none are speaker wires. Makes more sense.
So onward. There are a bunch of speaker wires that go under the seat. So I need to remove the seat. Thankfully it went forward and backward enough for me to get to all the seat bolts (the seats in The Mistress didn't and caused me all kinds of problems). But remembering the weight of the seats in The Mistress, I knew I shouldn't be lifting it myself so I got my neighbor to help me get it out.
Here's what's under the seats. Will keep me busy for a while.
We have some very cold weather coming. Not sure if I'll warm up the basement garage or not.