Where does the yellow/green wire go ? I realize it goes to the +12 at the fuse box eventually, but from where, as its only a short wire (120mm long) with a clear insulated spade terminal on it. I have tried the search function, but could not find anything relevant.

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1970 Mk2 Cooper S under restoration

See page n-20 in Mini W/Shop manual TP 832 1971.

Probably from the heater motor to the motor switch.
The wire from the fuse block to the heater switch is green - No 58 on the diagram.
The wiring diagram doesn't show the wire colour for this but green/yellow is also used for one of the wires between the wiper motor and wiper switch.
The MK 1 diagram doesn't show this wire colour either.

Hope this helps.
RonR
RonR

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68 build Mk1 Cooper S
72 Clubman GT project. Total restoration required

Thanks Ron for your reply. Green/yellow from the switch goes to +12, but where does this feed from ? On various schematics, the heater switch goes directly via a green wire to the fuse box. I have an un-molested loom and not a green wire in sight to plug into the spade terminal. My bet is the wiper switch or light switch - just want to confirm.

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1970 Mk2 Cooper S under restoration

I've just had a look at a MK2 heater I have and the short green and yellow wire comes from the heater switch and should go to a green or maybe green and yellow wire behind the switch panel or instrument panel. This wire should have a male spade/Utilux type connector on it which plugs into the female connector on the short green and yellow wire. This wire then goes to fuse A4 on the fuse block.
Well according to the wiring diagram it does but there is a big gap between the wire at the switch and the wire at fuse A4. The wiring diagram doesn't show the intermediate connector or wiring.
Also the short green and yellow wire from the heater switch doesn't rate a mention either.
I thought it may have picked up 12V directly from the ignition sw with the ignition ON but that doesn't seem to be the case.

Edit: It won't be from the wiper sw as it doesn't have a 12V ign On supply to it as the MK2 used the OZ Lucas /Preslite 12AUW wiper motor which has a 12V supply directly to it and not via the wiper switch. It's a permanent magnet motor with regenerative braking.
It won't be from the light sw either as the lighting circuits aren't fused at all.
See a bit more info about the wiper motor on my recent reply to the post about the wiper arm sweep being too large.

RonR

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68 build Mk1 Cooper S
72 Clubman GT project. Total restoration required

On my '70 S, there are 2 Green/yellow leads coming out from the heater fan switch; 1 goes to to fan motor. The other goes to a terminal on the lighting switch - only a short trip.
The lighting switch takes 12V from the solenoid via the ignition switch.
But I thought the fan motor only ran when ignition is ON. The lights work without ignition ON.
Should connect to No.2 on Ignition switch to operate only when Ig is ON?

Unless the wiring diagram is wrong, an alternative connection could be to terminal 2 on the ign sw which is live when the key is turned to the On position. But if the heater fan was supplied from the ign sw it would be unfused and that isn't likely.
It shouldn't come from the light sw either as it is unfused and always has 12V supply direct from the battery connection on the start solenoid.

It should come from the fused Ign ON terminal A4 at the fuse block and be solid green.
The only Ign ON unfused circuits are to the ignition coil and the SU electric fuel pump from terminal A2 at the fuse block and they should be white.

The Lucas standard wiring colours are solid Green coloured wires are Ign ON fused 12V supplies, from terminal A4 of the fuse block, to devices such as wipers, heater fan, stop light sw, flasher etc.
Green with trace colours are generally after a switch or device.

In addition, car electrical wiring doesn't always have the switches on the live side. Sometimes the switch is on the earth/body side of the device. (Ok for 12V DC but not for 240V AC wiring.)

Here are a couple of web sites with info on Lucas wiring colours which may help.
http://www.autoelectricsupplies.co.uk/c ... rder_2.pdf
http://www.speedycables.com/greengauges ... lours.html

RonR

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68 build Mk1 Cooper S
72 Clubman GT project. Total restoration required

On reading my wiring diagram, "miniron" is correct that there should be a green cable from fuse A4 to the fan motor. Will look for it at first light to see where mine is supplied - light switch does seem a bit odd.
The Mk1 S (generator) has the heater fan motor supplied from Ign. No. 2

That was my interpretation too. The short green/yellow wire is only long enough to go to one of the switch panel switches. I can remember in the far distant past (early 80's) when I took the front screws out of the heater and let it swing down, it was connected to one of the switches. Seeing I have the whole loom out on the bench, its too easy to run an extra green wire from A4 fuse terminal (and then it will be fused).

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1970 Mk2 Cooper S under restoration

My wiring diagram shows 5 green wires at fuse A4: to flasher, reversing light switch (ex- police), stoplight switch, instrument regulator and heater motor.
Had a look at my fuse box and only find 4 green wires (and 1 for tacho).
Maybe the heater motor was picked up from somewhere other than A4. Especially as heaters were not fitted standard until Dec 1970 according to John Sneddon's book, so maybe Ss had improvised wiring until until heaters were included in the wiring?. I know that coopers all had heaters but Mk1s picked power from Ignition switch.

The short green with yellow trace wire connects to the ignition switch for power.

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ex-NSW Police 1970 MK II Cooper S
VMCI #43

Thanks winabbey, that solves it. I just looked on my bare ignition switch and both terminals that are common-ed for the switched white wires have had terminals on. Its contrary to the N20 and Gregorys schematics. What are your thoughts on running a wire from fuse A4 to the radiator fan (per schematics) or at least putting an inline fuse in the current orientation ??

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1970 Mk2 Cooper S under restoration

If you are not fussed about originality I think the general consensus is to add relays, fuses and upgraded wiring in line with more modern vehicles.

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ex-NSW Police 1970 MK II Cooper S
VMCI #43

Endeavoring to make it very original. What isn't, will be easily changed back and for all the parts renewed, the old are being kept.

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1970 Mk2 Cooper S under restoration

Following on from this topic, can anyone enlighten me on the earth wire for the heater fan motor. I’d like to know the original colour and where it gets the earth from. The electrical schematic diagrams don’t provide any info in respect to this.

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1970 Mk2 Cooper S

On the Mk1 I'm working on, the heater motor (which is a white cable) goes to earth through a black joiner socket near the steering column and near the joiners for the blinker/horn leads. I know that doesn't answer for Mk2 but will try to look tomorrow.