Hey,

Is there a way to identify which harness belongs to which part number? Looking at ordering a new one from autosparks.

Problem I have is previous owner loved to mix the 200tdi with the 300tdi.

I want to just run a new loom to everything in the engine bay / lights etc, they're all rotten with water ingress and for the sake of It I cbf making a new one.

Thanks in advance.

The plugs on the harness are different from 200 to 300.
Post some photos of the connections in engine bay where the looms join up
Also at the rear where they connect to the lights

200Tdi harness uses old-school lumps of rubber with bullet connectors and direct wiring into the lights, whereas the 300Tdi has slightly more modern hard plastic plugs and connectors that allow you to disconnect the lights.

To replace the loom for the lights in the engine bay is a new main wiring loom (the most expensive one), and the engine is a separate one. You can fit a 300tdi loom to an earlier model but you just need to change more things (lights) and make sure all the looms match. I have just fitted late model 300tdi looms throughout my '89 110 but I was replacing all three looms and the lights as part of the rebuild.
Auto sparks are very helpful and a call with them will probably give you just as much guidance if not more than you will get on here. But certainly some pictures of connectors will help.

Also the 300tdi looms are not all the same with the later model 300tdi (what i have just fitted) using the newer style white multi pin plugs for the dash switches (indicator/wiper) rather than the black rubber bullet connectors. so even if you know it is a 300tdi loom you have currently you need to know which variant.

You can see here the connectors and plugs used on a late model 300tdi loom as I documented and asked lots of questions about it during my rebuild: LINK post #372 onwards is the discussion about wiring loom connectors with lots of photos.