Thanks for the update. I wonder if a relay contacts are stuck in the Make state? The coil will still make the clicking noises but current will always flow through the welded contact pair. Those relays are quite hefty so it is not likely, but you never know!
If this box can be connected to the loom with its cover removed then it may be worth soldering some LEDs temporarily on the coils and contacts to ground. That would be useful. Of course if you use normal LEDs they will need a series current-limiting resistor each.
Let me know if you wish to try that and I will chuck in, FOC, some LEDs and resistors with your TSM package.
