C3 1969 - Rear Loom question ❓

[Blondie69]

Hi all,
I've not posted for a while as digging deeper into the interior of my C3. Carpets out and I'm looking at the rear loom. I haven't got a wiring document yet ( as my search has revealed no shipping to UK) so I'm hoping someone may have some advice for me.
One particular black wire within the loom seems to have got hot and melted the plastic tape, in more than one place but I'm not sure if it's okay. The door ajar wires have been cut ( at the bottom of the lom) so it maybe that's why. But I thought I changed chuck the question out to you all and see if anyone has come across this.
I have attached a photo. The one stuck to the orange wire. Any relevant comments welcome

 

[Blondie69]

I've tracked it back along the loom and found a mess of black wire and it's the same one
Second question - does anyone know a auto electrician??? .
Or can it be taped up again and not get hot?

Many thanks

 

[Oneball]

Assuming it’s original, black wires are earths. I think I’d want to replace the whole wire unless I could determine why it has melted.