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Sorting out the wiring loom

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I've started to work through the wiring loom on my 1989 90 and hit a stumbling block.

I've got everything labelled up on the rear chassis loom now and have 11 wires in total, but there are still a few bits I'm stuck with.

1. Red Yellow - fog light

2. White Purple - ?

3. White Slate - fuel gauge transmitter

4. Purple - permanent live

5. Red Orange - RH tail light

6. Green Purple - brake lights

7. Red Black - LH tail light & number plate light

8. Green Black - fuel gauge transmitter

9. Green White - RH indicator

10. Green Red - LH indicator

11. Green Brown - reverse light

I've got the 3 correctly coloured wires already connected to the top of the fuel tank, why would there be duplicate ones as far back as the rear crossmember?

Could someone kindly explain what the white and purple wire may be for? I had a look through this thread to check my labelling was correct, but there is still no mention of a white/purple version


Thank you in advance,


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the chassis loom is common to 90 & 110 models, no point in making a short loom for a 90 when the longer chassis of a 110 needs the same loom LR just use the 110 loom to make production easier & no chance of a short 90 loom ending up in a 110 which would create production line hold ups.

White/Purple trace is for fuel pump No 1 or right hand pump to changeover switch -- not required on a 90 with 1 fuel tank & mechanical fuel pump.

have a look at this colour code list http://www.autosparks.co.uk/index.php?content_page=48

Edited by western
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Perfect, thanks guys :i-m_so_happy:

I'm working through the front lights now (expect plenty of stupid questions soon...)

Got most of them nailed down, however I seem to have a wire running down the LH wing that doesn't match up to any wiring diagrams.

It's black with a purple trace which Google seems to think is for the temp switch to warning light. I would have expected this to come out in the centre of the bulkhead but it runs past the heater and along the front wing with the rest of the LH light wiring. Any ideas as to what this may be?

My temp gauge used to work prior to dismantling the vehicle and since the rebuild has been connected back up to the same plug it was on so I'm a bit lost.

Edit: the black with purple tracer follows the wiring loom down the LH inner wing, with a ring connection that attaches to the inner wing with the rest of the black earth cables for the headlights etc, however it still doesn't show up in any of the wiring diagrams in the Haynes manual.

Thanks again,


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there's a Purple with a Black tracer which is the horn wire, which runs along the left side, the standard location for the horn is on the vehicles left front in front of the radiator.

can't find any black[purple trace wires in my wiring diagrams, my 110 is a '89 vehicle too.

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Thanks Western, I've got a purple with black trace for the horn already so it can't be that, but no diagrams seem to feature this other one so I'm stumped.

I've got a mate coming round with a circuit tester later so we can investigate it.

In the meantime I'll connect it back up the the earth point as it was.


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It is connected to the earthing point on the nearside inner-wing, on the same bolt that the headlights etc are earthed too. It runs back down the wing with the rest of the headlight wiring. When it reaches the heater, it runs with the main wiring loom along the bulkhead (parallel with the clutch pipe).

I'm confused because it is wrapped into the loom with the original loom wrap, so appears to be a factory fitment.

It's also a very small gauge wire, half the size of the indicator supply. Did 1989 vehicles possibly have an electronically controlled radio ariel?

For now I've just connected it back up as it was, all the front lights seem to work so I may just leave it for now...we have much bigger problems with the rear loom :angry2:



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Ok not to worry, thanks Western.

I've found a fairly large brown wire that is wrapped into the offside headlight loom, terminating just past the brake master cylinder.

It seems to be live continuously, even with the ignition turned off but is difficult to identify from the wiring diagram.

The diagram shows it as going via the fuse box and round in a circuit but it doesn't seem to provide power to anything in particular, does anyone know what purpose it serves?


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