Hi All,

New to the forum. Not my car but I'm in the process of checking over a wiring loom for a friends of my dads. As the thread title suggests it's a mk4 RS Turbo S2, registered in 1989. He's in the process of restoring the car and the looms been lying in a box for 25+ years so he's asked me to check it over before it goes back in the car. Very few of the connectors were labelled so I've been using the diagrams within the haynes manual and have been carrying out point to point continuity checks to work out what all the connectors are for and label them up. Now I'm 99% of the way there but there's a couple of connectors and cables I can't identify from the drawings so was hopeful someone on here may be able to assist....


1: There is a circular 3 pin connector that connects to the loom near the fuel pump connections. The 3 cores are brown, brown/black & brown/red.This connector is part of a short loom piece which connects to the main loom through another 3 pin connector. The short loom has a ford label with "87AG 014406-AA", from a google search I'm fairly confident this connector is for the "fuel tank sender unit", however the wiring diagram I have "Fig 12.85" from the haynes manual only shows a 2 pin connector going to the fuel tank sender unit ( brown & brown/black). It shows the "brown/black" core connecting to the instrument cluster via connector "C-900". There's no continuity between the brown and black connector on the 3-pin plug and C-900 though but I'm not sure if that's because the wire is broken or because the drawing isn't accurate (the drawing doesn't show the brown/red core so I'm doubtful if it's correct). I've physically traced the brown/red core from the 3-pin plug and it connects to another 2-pin connector (brown/red & brown) in close proximity on the loom. I'm not sure what this 2 pin connector is for either as I can't see it in drawings. Is anyone able to confirm what these 2 connectors are for and where they should connect to?


2: There is a Red/Blue core, quite a heavy gauge (approx 2.5mm^2 at a guess). One end has a single black connector that's close to the connections for the radio. I can physically trace the core until it enters the main loom of cables that goes into the fusebox. I cannot find this Red/Blue core within the fusebox though so I'm thinking there might be a connection inside the loom where it either splits into multiple cores or changes colour. I can't find this core on any of the wiring diagrams I have either. I'd rather avoid splitting the tape to open the loom up and physically trace the core if I can avoid it. Does anyone have any idea what this core might be for?


3:On Fig 12.103 for the ABS system the diagram shows a single brown/green core coming from pin 87 on the ABS relay L6 and going to "Hand Brake Contr Switch". This loom has 2 "brown/green" cores connecting to pin 87 on L6. I've traced the second core and it goes to the brake fluid level switch through what appears to be a diode. The diodes in a black rubber connection and physically is located on the main wiring loom a few inches after it exits the rear of the fusebox. Fig 12.103 doesn't show this diode connection between the fluid switch and ABS warning relay. Instead it shows the fluid level switch connecting to a second "brown/green" core on the handbrake switch. I cannot find this second core going to the handbrake switch.


If anyone could provide guidance or additional info on any of the 3 points above it would be greatly appreciated! If required I can take some photos as I've got the loom spread out across the dining room table at the moment, much to the delight of my gf! Thanks in advance!

 

it will be far easier with pics

 

Bottom two connections are what I believe to be for the fuel pump. Other connectors are the ones I can’t identify on drawing although think the 3-pin connectors for fuel sender unit.

Two connectors for instrument cluster, ‘c-900’ on wiring diagrams. Diagram I have shows fuel tanker sender unit connecting to here via brown/black core.

Two pin connector. (Brown and brown/red). Not sure what this is for but the brown/red connects to the brown/red on the 3 pin plug that i think is fuel sender unit so assuming related.

Label on short loom piece that I think is for fuel sender unit.

Mystery Red/Blue core at top of image with black connector. Other cores which exit the loom around this area are for radio and passenger door switch.

Short piece of look showing 3-pin connector connecting to main loom via another connector.

ABS warning relay on left (green). The brown/green wire comes from pin 87, goes through diode (black rubber tube with white tape attached) and then goes off to brake fluid level switch. This wiring isn’t shown on diagram I have

 

You've correctly identified the fuel pump connectors.
3 pin is fuel sender
2 pin I'm unsure but suspect fuel computer

Red/Blue IIRC is glovebox light

 

Thanks for this. I’ve made a small amount of progress since my initial post. The haynes manual I was given with the loom and I’ve been using for the diagrams is the owners workshop manual (purple cover). I found a second manual yesterday, the service and repair manual (red cover), managed to find a pdf version online and the diagrams in it show both the diode wiring on the ABS circuit and the 3 pin fuel sender wiring. As you correctly identified the brown/red goes to a fuel computer, however I don’t think the car this looms from has that as theres several other cables going to the fuel computer which aren’t on the loom.

they also show the brown/black core going back to the instrument cluster as did the other diagrams so looks like I’ve maybe got a broken core there, which I’m surprised at as all the other cores within the main loom have belled out ok with a meter.

i still can’t identify the red/blue core though. These new diagrams show the glovebox light as being grey/black so I don’t think it’s that. Given the csa of the core I’d be surprised if it was just for powering a lamp. From memory I’ve already got the glovebox light marked as another core, will check later. Think I may have to split the loom and eyeball it to see where it goes.

finally, don’t suppose anyone has a copy ot the red haynes manual they’d be able to send a copy of page 245 please? It’s the diagram that shows the wiring for the radio and also shows the key for fuse sizes and core colours etc. for some reason this page is blurry (and prints blurry) on the pdf version I found online.

thanks again.

 

Thought I'd provide another update on this on the off chance it helps someone in the future.

Split open the loom and found the Red/Blue core connects to one of the permanent lives direct from the battery, I think at common connection S-1012. It's difficult to make out from the diagram as the pdf copy I have is blurry however I think this core is a permanent live feed to a graphics equalizer unit for the radio.

The brown/black from the fuel sender unit does go back to instrument cluster C-900, I found a damaged section of the loom where this core was completely severed.