Mystery plug

Definitely not that but similar 

My bad, the wires are actually brown / black which is live with ignition & a black earth. Did Japan spec have anything different, my headlights have rover Japan part stickers but I dont have any history for the car to confirm. 
 

1275rob wrote:

My bad, the wires are actually brown / black which is live with ignition & a black earth. Did Japan spec have anything different, my headlights have rover Japan part stickers but I dont have any history for the car to confirm. 
 

Are you sure that isn't orange/black?  Brown is usually much darker.

It does look like orange/black to me too..brown is darker I believe.

Japan is a right hand drive country, so it's likely that the headlights are replacement units, given that the headlights are a commonly replaced part as they're next to bloody useless, I wouldn't mind betting that the headlights are new old stock items reimported back to the UK from Japan.

Could be orange & black tbf. Oh well it will remain a mystery for now & doesn’t appear to be doing any harm. Thank you all for your advice & have a Merry Christmas 

My car is also a 97 build and it too has brown/black & black wires in a 2 pin gray plug
Now the only brown/black wires that I'm aware of are for the engine bay fan, but mine hasn't been connected to anything either and the engine bay fan works, so my best guess it that given both our cars are 97s there by relatively early cars that at some stage there it was planned that there would be extra engine bay cooling that our good friends the bean counters decided late in the stage to delete the extra cooling fan in order to save a few shekels and the wiring plug is still there.
When I have the car back together I must check to see if the brown/black wire is live when the engine bay fan is running. That will pretty well prove my theory correct.

Thanks Cobber, i might install another fan then I checked the plug with a multi meter and the brown / black wire is live with ignition on.

if it is a engine bay fan wire it should probably only be live when the fan engine bay fan is actually operating when you do the test to see if it's live the + probe should go to the brown/black wire of the plug and the - probe should go to the  black wire of the plug not to a general ground.  If it's live when the engine bay fan hasn't kicked in yet then then who knows what it's for. the reason you need to use the - probe on the black wire and not to ground is it may switch to ground through the  black wire if the brown/black wire is always live.

If you look at the dog's breakfast of wiring diagrams in the workshop manual on the engine management pages you will see there is a brown/black wire running from the engine control module to the engine bay cooling fan relay.
Then look at the cooling fans page you'll see a brown/black wire running between the engine control module and terminal 86 of the engine cooling fan relay via terminal 6 of connector CO1448 black plug
Unfortunately the printing quality is totally shit in my manual (cheapskate bastards) as it is blurred a bit on some of these so they might not be right but,as best as I can tell,
These are the only brown/black wires I can find in the workshop manual
It depends on which version of the engine control module the car is running  as to what terminal is used at the module.
MPi versions use terminal 26. of wiring connector CO159 black plug
VVC versions use terminal 32 of wiring connector CO158 red plug
Where as EMCVT versions use terminal 74 of connector CO634 black plug

To allow for the different engine control modules to be adapted, there is another pair of connectors blue plugs that link the cars loom to the various engine control modules, these are CO162 (Car loom side) and CO448 (module side) these use terminal 8

Interestingly enough there seems to be no mention of our mystery grey plug with brown/black and black wires, which suggests that it is not used. in our application. it may even be part of a generic piece of wiring loom used in common with other MG/Rover cars that use some of the same parts.

I hope that makes some sense.
The manual is so poorly written it really is all over the place like a mad woman's shit! the crap low resolution black and white photos don't help either.
I've been staring at this shit so long I fell cross eyed, I need time to absorb this fully... if I come up with any revelations or insights I'll report back.

Upon reflection I doubt our mystery plug would be used on other MG/Rover cars as none would be likely to need an engine bay fan.......but the Lotus Elise might.
Now I might be able to get some bloody sleep!

The circuit diagram downloadable from the information department implies coverage of Mk1 f cars up to MY2k, it doesn’t cover earlier cars. When referring to the diagrams for Mk1’s, which I do often,I have this open & also the one on Dieter’s web site.
This is monochrome & takes a bit of getting used to, the effort, however pays off.
As an example; I’m farting around with the electric windows, moving the switching from its historic home, hiding behind the gear stick, making themselves difficult to both see & use. I’m also fitting one shot opening & closing on both passenger & drivers windows. The switches have found a more convenient home on the door cards.
The early cars didn’t have a drivers one shot window & sure enough this module is absent from Dieter’s diagram. It is on “our” diagram.
Early car owners should be aware of this version as there are a number of discrepancies.
M