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

Hi all,

I know this was covered in my fog light mounts post, but I'm still struggling to find my fog light wiring in Monty's loom (2012 Duratec Plus 4)

All I can find is this connector....



And this, which I guess could be heat shrink hiding the wiring I'm looking for?



I'm super keen to light up my lovely Marchal fog lights.



Can anyone help me locate the wiring to make that happen?

Thanks, Dave.

Not sure if helps but on the same age Roadster the wiring diagrams are here

Have checked again Dave as well as looking at diagram link John posted above and advice is the same. Under the o/s front wheel arch should be a pair of blue/yellow wires 380mm from the point at which they break out of the main loom conduit running aft. Each of these wires should terminate in a male bullet probably protected and joined by a double female bullet connector. The second wire provides a loop to the n/s for that fog lamp.

My car is not on the ramp at the moment to confirm but recall seeing such wires doubled back and cable tied out of the way, but it was a while ago.

Not sure of the orientation of your pictures but below is one of the extra sidelight feed I needed for switchback LED bulbs. Hopefully you can place the area as top suspension cross arm is shown.



You can just see the bullet connector normally there for optional wingtop light and the short red wire I added to new three way connector. It would be worth looking in this area since your foglight wire should be in same grouping.

Hi Richard,

Thanks for your ongoing support, I just wanted to double check as on British cars a blue wire with a yellow trace is normally used for long range driving lights (switch to lamp), for the equivalent circuit assigned to fog lights the British standard would be a red wire with a yellow trace. That aside I'm sure there's some variation in the standard as it's the great British motor industry after all, and Lucas the prince of Darkness was known to take a fairly lax approach to the rules

I now have to admit I've been trying to find the circuit by lying on my back looking up into Monty's front wheel arches, clearly this isn't the best approach, so I'll now proceed to jacking and supporting the car before removing the o/s front wheel. This should give me a fighting chance of locating those elusive pair of blue/yellow wires. In my defence I've been hindered by Waxoil, all surfaces under Monty are covered in a sticky brown/black coating, this is good for corrosion protection but not ideal when trying to find wires of a specific colour

One last question regarding grounding, am I correct to assume the blue/yellow wires I'm searching for are the live feed and the fog lights Morgan used (if fitted from new) would have grounded through the lamp itself to the car body? I ask because rather than grounding through the lamp my Marchal fogs each come with a separate red live wire and a black earth wire, so if I'm assuming correctly and the Morgan circuit is a switched live rather than switched to ground I will need to ground the black Marchal wire to Monty's chassis/body?

I'll certainly steer well clear from grounding to the engine block for fear of generating any voltage offsets/earth loops that could play havoc with injector durations and or the crank position signal, been there done that with my TVR and it wasn’t fun!

Thanks again everyone

Dave.

If it's easy to provide fog light ground locally suggest doing so. Then just hook up the blue/yellow to red wire each side.

To this end, no the blue/yellow wires are not permanently live they are controlled by the dash wiring which is already in place to an unused connector, allowing the optional fog light switch to be added. I may have mentioned this earlier. The actual electrics/electronics between switch and feed to lamps vary according to age of vehicle from direct feed to full BCU (software) control on those from around 2014 on. Note either before or after switch there will likely be built in control such that auxiliary lights are only powered with headlamps on to comply. The switch warning light will reflect this.

The inclusion of front fog light (blue/yellow) wiring within front part of chassis loom has been a feature of the Classics from at least 2006 and probably earlier. This is why I'm suggesting with a good degree of certainty they exist on your 2012 car. The wire colour codes are academic since MMC use same wires for long range spots or fogs. In any case the red/yellow colour code you mentioned is used for rear fog light wiring only. Even left and right headlamp wire colour codes are individual nowadays.

I agree that finding these redundant wires can be difficult with the monochrome effect courtesy of MMC spray on underseal but you definitely need to be looking with front wheels removed both sides. Look along base of inner wheel arch and remove a few cable ties if it helps.

Good luck.

Dave, are you trying to wire the front fogs to the same circuit as the rear and use the same switch?

If you are something to consider…. The pcb that controls the fog lights with its dodgy relays is a just tad flakey. There are numerous reports of the fog lights (pcb) failing and mine have too. One day the fog lights decided to come on and stay on no matter what I did. So to enable the car to pass the MOT I’ve wired my fog to a temporary switch with a separate new circuit that is only live when the lights are on.

Long term my plan is to abandon the pcb but keep the same dash switches and have a more conventional control box under the bonnet, but that's when I have more time….

Excellent advice from you both, Richard & Rog.

Yes, I intend to use Monty's column switch and the Morgan wiring, so it’s helpful to know the PCB that controls that circuit can be problematic, I assume/pray the circuit does also include a traditional make/break relay so it would be helpful to know where it lives?

With the wheel off I'm confident I'll find the illusive blue wires with a yellow trace, but it'll have to be done this weekend when I have a window of time with some daylight, I'll ground each lamp to chassis as recommended and make up a grounding loom if it makes sense to do so.

I certainly can't wait to light up my beautiful Marchals

Thanks again for all your help chaps, the Morgan community is definitely a great bunch


NB: Briskish standard automotive wiring colours can be found here, but these are probably as out of date as my knowledge

https://www.minimania.com/pdFile/wiringharnessoverview.pdf

Rog, it seems that Classics and certainly +4 and Roadster have had provision for independant front fog light wiring and switching since at least 2006. It doesn't make sense therefore to put extra load on the rear fog circuit given as you mention, the fragility of control circuitry on PCB models, although since around 2014 they have used sealed BCU control.

I think the need for front and rear fogs differ slightly as well depending on conditions. Certainly our F54 Mini has independant controls for such.

Having looked at one of the PCB variants it would be an onerous task to re-engineer it exactly. Going back to basic relays and such kept out of the way of leaks is the way to go. Downside, the final result would be much bulkier but a fun project.

Not sure why you would want to do that given the extra wiring Dave, but your call. Remember extra load's will be placed on headlamp and maybe dip switch, assuming you use halogen bulbs for both.

My advice has been based on the assumption you would source and fit the optional front fog switch and use the existing plug and play behind dash connector. This is what MMC would have done if front fogs or spots had been spec'd on new car. If you want to go this route, once you have sorted and wired the lights at the front, you will need to drop the dash. There you should find an unused 8 pin connector with just two wires leading to it, red/orange and wait for it, blue/yellow, and yes have traced this to the front of car As a test it will do no harm just to jumper these two connections together to simulate simple toggle switch and check to see your fogs light up. Note you will need to have sidelights on first though.

As far as I can see the auxiliary front light wiring/switching doesn't involve anything to do with the PCB Rog mentions or indeed any relay.

Richard I haven’t see anything ‘concrete’ to suggest that is not what they have done. The front fog functionality (ie.not on with main beam) could have been built into the pcb utilising those little 12A pcb mounted relays

Please please let me be wrong…..