Dip/main Beam Query

[David Parkes]

All my electrics seem to work OK apart from one thing that I'm not happy about.
When I put my main beam on the dip beam goes off, this in turn has the effect of turning off the fog light if it has been selected (as the dip beam power is cut).

But, when I flash my main beam, the dip beam stays on.

Do everyone elses lights do the same?

I did speak to Tony about it at Pilgrim and he thought they were fine, but my Audi and wife's SEAT certainly don't turn off the dip beam when the main beam is selected.

Help please!

[tonym]

Morning David, quite a few "Modern" cars only have either main beam or dip beam and not both. also a lot turn off the fog light when the main beam is on, why would you need both? If it's that foggy that you need the fog light on then you shouldn't be using the main beam!

[David Parkes]

So everything is OK then? Please say yes

[tonym]

Yep, everything is fine, don't worry, just enjoy driving the hell out of it

[SimonP]

David,
That's the way it's supposed to work for H4 headlamps which have main and dip filaments in one bulb.
If you ran both filaments together, you would overheat the lamp glass.
It's not a problem though for the couple of seconds you'd use the "flash" facility.

Where the car has separate main and dip bulbs, the dip stays on when main is selected, to give better lighting of the road.

[SimonP]

And for the fog light...
This is compliant with the regulations.

Some countries' regulations (eg USA) state that the fog light must ONLY work with headlamps on dip beam.

BUT our SVA and MOT aren't as choosy - they say the fog light "must be tested when the headlamps are on dip beam".
Doesn't say anything about whether or not it is permitted to work with or without sidelights or main beam etc.

I think as standard the GD fog light can be switched on at any time, but I modified mine to work only with dip beam.

Simon.