Hello Getaways- I thought that when the fog lights are turned on, the HI beam lights were to be turned off, so that only the LOW (main) lights, and fog lights are on - which it seems this is what is happening on your car per your description.
Thank you, I really appreciate it. In my defence, I’d had a couple of beers when I won the auction on Car and Classic 
And it does look nice
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When you say main beam, to me that means all lights would be working, I use either (main/high) to be the same.
I started this thread and it has become very frightening … you guys are scaring the bejesus out of me !
Iv’e just purchased (2) outer 7" Lucus P700 H4 tripods as an upgrade to existing 5/34".
Also purchased (2) inner 5/34" Hella 5001A H1 to replace my sealed beams.
I’m about to hand over to my mechanic, so how do I explain what he should do ? Does he put a relay before the ‘Hella’ relay (what size) and then (1) on each wire to each lamp or groups (ie. (2) innner, (2) outer) or combinations (ie. (2) sets of (1) inner and (1) outer) ?
Seems that if we don’t get this right, I’m starting a fire in the engine bay !
I mean switch in 9 o’ clock position. All four headlamps on, normal driving ( dipped beam), but not high you get by pulling the stalk.
Dipped beam should be only the two 7“ and on european cars the dipped beam is forced to turn on in the fog position.
If you pull the stalk all six will be on until you let go.
If the inners are on with the dipped beam you need to look into everything. Car looks solid.
The way I did it the 4 fused relays replace the fuse box. Or two relays switched by blue red on each side and a more substantial line from one of the battery posts on the bulkhead or alternator.
It’s simple, just make sure it’s fused somewhere somehow and that one driving light stays on if a fuse blows.
You’ve got that law in Europe too? Completely defeats the point of having fog lights, which are intended to be mounted as low as possible and to be the only lights on so as to send light under the fog layer and minimize glare back into the driver’s eyes.
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The right and left outers are separately fused with 10A in the left wing mounted fuse box. A 5A or less will inevitably blow. The high beam, inner and outer, are separately fused, left/right, with 25A. The fuse box you show is not related to the headlights - and eventual trouble here is a separate problem. But also; the reason for lack of power to some wires in the fuse box shown, it might be just because the item served s not turned on…
If you have an extra step, ‘fog’, on the light switch; Japan probably uses the ‘European’ set-up. Which means that the light switch directly powers the outer, low, beam directly - with no power from the light switch to the relay. Which means that in ‘fog’, the relay does not deliver power to the headlamps, and does not switch between ‘high’ and ‘low’ with the stalk - though the ‘flash’ function still operates. ‘Flash’ is powered from constant power - the ‘flash’ works irrespective of light switch position…
So in ‘fog’, the inners/high beam remain unlit by intent. The reason for this is that fogs are only allowed to be used in foggy conditions - where high beams are counterproductive. Additional, you may have rear fog lamps (check?), standard in Europe - and if so; if you follow a car with rear fogs in clear weather, the glare will drive you homicidal…
If the headlamps otherwise malfunction - it’s to be pursued as required…
Frank
xj6 85 Sov Europe (UK/NZ)
I’ve ordered a cable tracker to find exactly what goes where 
Thanks everyone for all you input.
Hmm … Cable tracker ?
AKA power probe. Screwdriver like device with a ground wire. Attach the ground wire to a ground. probe the suspected cable. if it is powered, the handle lights up!!
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It was the term ‘cable tracker’ that confused me.
Thanks for clarifying.
I have one like this for RJ45 which is excellent, hoping this will do the job for single wires, reviews say it will - I’ll let you know how i get on.
https://www.amazon.co.uk/gp/product/B073XLV9BM/
not the law in the UK although the number of people who keep their fog or driving lights as well as their headlights would make you think t was!!
The law doesn’t forbid having both sets on but fog lights are only permitted in foggy conditions although again you wouldn’t think so! Having the dipped beams on as well as the foglights negates the value of foglights as you say.
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And me, Derek…
Having its own power source means that it can check continuity between two points - verifying intact connection and help to identify which cable/wire is which. However, the same care applies as with ohming; ‘all’ car wires wind up to ground - so disconnection is advisable. The tracker is not a substitute for an ohmmeter - or for a test lamp for checking powered circuits…
Frank
xj6 85 Sov Europe (UK/NZ)
Actually not the law here either (parking lights plus fog lights are okay) but my cars don’t allow it. I should maybe change that as they’re definitely pointless when the low beams come on with the fog lights.
The S3 had a separate wire bypassing the relay like Frank said and the Mercedes needs the lights to be on so I can pull the switch to fog…
yes, but, at least in mine, also with just the side lights, so you have both options.
Same with my Range Rover
Hi,
FWIW the Jaguar Mark V has fog lights as standard. Designed in Coventry, England, it is wired so that Fog lights can only be on with the light switch in the sidelights position, NOT if the headlights are switched on. I have had no trouble with that, I don’t think they even tried the fog lights at MOT.
Cheers!
Right, the two red wires in the photo are connected to the inner 5 3/4" headlamps, referred to on the fuse box as “side lights”. Light switch in position 1 no voltage at the fusebox on the red/brown wire. With the switch in position 2, headlights are on and I got flickering on the voltmeter form the red/brown side light wire, switch meter from DC to AC and it was reading 20V AC at one point then a steady 3V AC (ignition is off), which is very weird, and not really sure how it is possible?
I’m think it must be a faulty switch, as I understand it there is one direct live to the switch, and switch outputs to the fuse boxes. (all the headlight fuses under the bonnet are good too).
As an aside, the outer headlights having parking bulbs in them too, and these don’t work at all either…