Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing Fog Light Wiring

Hi Richard, thanks for staying with me

Following your comments yesterday, I have two further clarification questions that I'll seperate out into two posts so they can be answered individulally.


CLARIFICATION ONE:




When I checked the two blue/yellow wires I'd expected both to be carrying +12v with the lights on, that is one to supply current to the O/S lamp and the second one to supply the N/S lamp.

However, clearly my logical assumption was wrong, what I actually found was only one of the blue/yellow wires was live, I used it to prove I could at least power up the O/S lamp from the dash wiring but remained confused as to why the second blue/yellow wire was showing 0v on my meter

So if I've understood correctly what you're saying is I need to connect these two blue/yellow wires together to create a loop as one feeds back to the dash?



And connect them together with a Lucas style 4.7mm double like this?



So I can finally run new wiring forward from the double connector to supply +12v each lamp?

CLARIFICATION TWO:





I believe what you're saying here is there's more blue/yellow wiring to find in the N/S wheel arch?

And once found, I need to be bring it back across the to the O/S wheel arch where I would connect it to the Lucas style 4.7mm double connector that's also now also serving to loop the two blue/yellow wires I finally found yesterday evening in the O/S wheel arch?

Or, are you saying with the loop created the blue/yellow wiring still hidden in the N/S wheel arch will become live?

Sorry for all the questions, but it's not always easy to pull clear step by step instructions out of a series of paragraphs, probably just me being thick mate

Correct on all counts Dave although I did point this out several times in earlier posts

MMC make this easy for you by providing the double female bullet which serves to isolate and protect the male ends when the wiring is not used as well as completing loop to other side. I can only assume that a PO of your car saw fit to remove and add a cable extension for whatever.


Yes the other end of loop will be found under n/s wing. No need to "bring it back" this is simply the other end of blue/yellow wire providing loop of switched +12v from o/s, so both lamps illuminate together.

Only thing not mentioned was ground connection for fog lamps each side. I would be tempted to use another double female bullet to replace single on the black lead to headlamps unless you can find unused grounds elsewhere.

Traditional foglights draw a fair amount of current and unless the wiring is already run from a relay up under the dash it might be worthwhile considering fitting a relay and picking up power from a main powered line rather than through the foglights switch.
I guess this could be avoided if the foglights themselves or the bulbs are low current LEDs.

On my car I have the front foglights set up as driving lights and the relays are set so that they can only come on when the headlights are on high beam. I had this set up after discovering that I was sometimes inadvertently blinding oncoming drivers
I did consider using the old trick of having one foglight and one driving light but my experience of front fog lights is that you tend to get too much light reflected back at you from the mist so I thought just having driving lights was a better idea.

Out of interest Peter since you have a similar age Plus 4 , did you use any of the MMC dedicated lamp and dash switch wiring, relays aside?

Richard are those ‘plug and play’ blue/yellow wires fed from the o/s side light 7.5A fuse?

The wiring is essentially plug and play and the power does come from the sidelight circuit (red/orange wire) but via three fuses since the sidelight switch itself is fed by fuse 18 15A, then you have the 20 A fusebox fuse . The blue/yellow wires are only live when the switch is added and turned on.

I see why you asked though so yes it would be a good idea for Dave to up the o/s sidelight fuse 12 from 7.5 to 15 amp OR fit LED equivalent bulbs in his fogs.

Awesome Richard, and apologies for my short term mammary loss, I feel less of a tit now

Gotch-ya



Best to avoid this

I take your point about sharing the ground with the headlight, this is my current solution... no pun intended



Monty has lovely drivability, I wouldn't want to introduce anything that could interfere with that.

Slightly off topic but in the course of this thread I've referred many times to the wiring schematics published in the 2006 - 2014 Classics parts book available for download here. There are three iterations of the Plus 4 and V6 chassis loom shown but I've spotted an error related to fuse box labelling in the latest one dated 2007, relevant part as below.



The 20 position fuse box is labelled correctly running down the r/h side 1 - 10 but reversed on the l/h side. It should read fuse 11 - 20 running down l/h side to concur with fuse ident listing (not shown but to the right in full schematic) and associated cables/circuits.