Sorry, not forgotten about you, just been busy. I don't have a wiring diagram for a 2000 available but had a look at my own 2000 R. Unfortunately the Turbo has a lot more stuff in that area it is hard to see anything in there. Also when I did the PCV clean up I replaced a lot of the wiring covers wi...

I’ll have a peek at mine this morning, stay tuned

The brown colour and circular connector are consistent with a ground wire

Brown is typically a ground color in these cars.
I don’t have hands on experience with 2000’s,
but I would also suspect it belongs on a bolt.

If it is coming from a piece of wire loom, it might
be helpful to know what other wire colors are
in that section of loom.

The timing belt tensioner? Here's what I found in preparing for replacing mine: The tensioner is ambient temperature sensitive. The Haynes book says "Using a 6 mm Allen key, turn the belt tensioner anti-clockwise until its pointer reaches the stop to the right of the central notch, then turn it...

I had a nightmare first time I did this. I had bought an aftermarket kit from IPD and it included an INA tensioner. I spent 5 hours trying to get it to work but every time I tightened it it moved. Eventually gave up and went to the local dealer and compared to an blue box part. They swapped it for t...