Wire diameter differences

ph1978 · Oct 6, 2022

Hi All,

I have been reworking the rear light and tow bar wiring loom and decided to go with waterproof 2 and 3 pin connectors. In doing so I have come across existing pairs of wire that terminate in the original rubbered female bullet connectors, the question I have is why is there a difference in their diameter - is the reason because the thicker one (14AWG) is supplying two rear lights and the thinner (16AWG) is going to the left side to supply only one? If that makes sense?

Trying not to have to pull it all apart again if there`s another more critical reason !

Cheers

Dr Strangeglove · Oct 6, 2022

I have a 1993 90 if you want me to look at the wiring tomorrow. I just replaced my rear loom with 13 core trailer wire so the original is still off the truck if you want me to measure it.

ph1978 · Oct 6, 2022

Mines also a 93 but a 110 so should be the same, the part of the loom I am questioning is where it comes into the interior through the rear arch at the very end under the rear side window, this is where it has the old toblerone type connectors that some have two wire coming up and terminating in them - I am now assuming that the thin wire of the two simply goes back down and across to the LHS for the left side light/stop light. I will photo it and upload in the morning. What I have done upto now is cut off the old connector, strip the ends of but wires (same color/trace) and add a pig tail to them for the 2/3pin connector and solder/heatshrink them together. Other thing I have done is use a individual earth wire for each lamp from the 2/3 pin connector and plan to find a new solid earth point for them all.

Dr Strangeglove · Oct 6, 2022

I think you are correct from memory. I did similar with mine. I added a wire from the negative of my battery and took it to a multi-point in the back. I then linked that to another earth multipoint on the other side and did the same there.

I used another piece of 13 core over to the other (LH) side to keep the wiring consistent and this included an earth which I linked to the RHS earth point.

ph1978 · Oct 6, 2022

That`s really good to hear, was completely confused earlier on today but cracked on with it anyhow as I was sure I was seeing it right. Logic overcoming odd design! Thanks for the confirmation - I will upload some pics tomorrow in case anyone else has the same questions. Cheers bud.

ph1978 · Oct 7, 2022

Dr Strangeglove · Oct 7, 2022

This is from my rear loom, which is a 1993 90, but fitted with a 300tdi before I got it.

Purple - Perm 12v - goes to RH only 2.65mm

Red/yellow - Fog -to RH only 2.6mm

White/purple - fuel pump- direct to fuel tank plug (this does not go into the RH rear) 2.07mm

Red/Black- LH Tail- goes to RH at 1.84mm but then comes back and bridges to LH at 1.78mm

Red/Orange - RH Tail - goes RH only 1.84mm

Green/White - RH indicator - goes to RH only 2.03mm

Green/Purple - Stop - goes to RH side 2.33mm then brides to LH at 1.75mm

Green/Red - LH Indicator 2.00mm then bridges to LH at 1.74mm

Green/Brown - Rev - goes RH side 2.03mm then bridges to LH at 1.76mm

Green/black - fuel tank sender? - direct toward LH but goes to fuel tank plug (does not go to LH side) 1.53mm

NOTE - the fuel tank plug also has two black wires - one is thicker than the other. These join the loom and go to the LH side only. I presume these go to the earth on the LH tub, but mine did not have a rear fuel tank!

NOTE 2 - the sizes are in mm outside the insulation on each wire.

ph1978 · Oct 7, 2022

Wow thanks man - That`s a great source of info, I will measure with a vernier gauge tomorrow. Going of what you have described it sounds like the 90 and 110 have identical looms at the rear.

Dr Strangeglove · Oct 7, 2022

ph1978 said:
Wow thanks man - That`s a great source of info, I will measure with a vernier gauge tomorrow. Going of what you have described it sounds like the 90 and 110 have identical looms at the rear.

I did wonder why the left hand only wires went into the right hand side instead of just splitting over towards the left with the fuel tank wires, but that would make it difficult for the trailer wiring!

I ended up replacing my loom with a 13 core trailer wire as I don't need the tank wiring. My existing loom wasn't in great condition so this was fresh wire with the eight wires I needed included. It has an additional five wires, but one is a switched live which I intend to use, it has a spare which I may use for the rear wiper and then 3 earth's. I need to decide what to do with those. I am thinking I will use the standard 7 core trailer earth as a direct earh to the battery and then use the others for the heated rear window (if it works - has never been connected). My only issue is I don't like altering known wiring colours, which is why I used the trailer cable!

ph1978 · Oct 7, 2022

Yeah I bought same trailer wire for my repairs to the existing loom, mine was cut into below rear right side chassis and wrapped around it by previous butcher! when I was tracing issues it all came to that section which was damaged so bad there were exposed copper all over the place plus lots of the cable when stripped back was black and very difficult to get solder to into it.

Does your loom have around 12/18inches before it enters the rear arch a section of low temp solder joins all at the same place? Like the rear section is removable/replaceable?

Dr Strangeglove · Oct 7, 2022

ph1978 said:
Yeah I bought same trailer wire for my repairs to the existing loom, mine was cut into below rear right side chassis and wrapped around it by previous butcher! when I was tracing issues it all came to that section which was damaged so bad there were exposed copper all over the place plus lots of the cable when stripped back was black and very difficult to get solder to into it.

Does your loom have around 12/18inches before it enters the rear arch a section of low temp solder joins all at the same place? Like the rear section is removable/replaceable?

It does have some joints but I assumed it was a previous bodge. The permanent live was broken as was the left hand tail, so the new cable has fixed those. I did test all the wires at the split and all were working appart from reverse, which I presume is the switch rather than the wiring as it was working prior to me removing the rear crossmember, and also the LH Tail which was a broken wire just before the loom entered the tub.

Wire diameter differences

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