Defender Rear fog light not working on full beam

Trying to track down wiring fault on rear fog light on my 85 defender . Works fine on dipped beam , light comes on and dash panel lights up. As soon as full beam is activated both rear fog lamp and dash indicator goes out. Have checked wiring at rear of Landy , all good. But at the fuse and steering column power goes off when main beam activated . Suspecting the relay or some dodgy wiring. anyone had similar issue ?

Is that an added feature?
If its foggy enough for fog lights then using main beam usually blinds you.....I'm sure I had a car that did that as well?

It's rear fog lights , hopefully not blinding driver behind me ☺️

Pretty sure that's how it's meant to be. Full beam on gives fog lights off, same in any car (I think!)

John

Hmmm didn't think of that , I'll check it out on my Beemer. Circuit diagram might also indicate that. What's the theory ? Guess you wouldn't use full beam forward in fog ( you'd get blinded) but how does that apply behind u ?

Hmmm Beamer has rear fogs on when both full and dipped lights are on . Rang MOT station and inspector said it only needs to work with dipped headlights on . So guess all is good ☺️

Can't remember what mine does, but it makes sense- if it's foggy enough to need the fog lights on, full beams will hinder rather than help. I think there are cars wired so that front fog lights also turn the headlights off completely.

Sounds a bit too advanced for an '85! My '87 CSW's fog light stays on when full beam is switched on. Can't see the logic in the car needing to override the rear for you.

Mine does same

As mine or his?

fanatic said:

Mine does same

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As mine or his?