fog lights

[ianmayco68]

Hi all , is it legal to have front and rear fog lights on the same switch ? As in wiring through a carling off-on-on switch so rear fog light comes on at first switch on then the front and rear on the second on .

cheers Ian

[Bowie69]

I can't see why not, but you do need a dash warning lamp for the rear fog.

[western]

better to have them on seperate switches, as sometimes only rears are needed if visiblity is 100m or less. if you have a off/on/on switch then you need to decide if you want front or rear to be lit first.

 

[ianmayco68]

I was trying to cut down on switches , idea was rear fog as that's mandatory wired to first on , front to second on as they get used very occasionally and means fronts can only be used when rear one is on . According to the wiring for the switch pin 10 links to pin 4 which is power one out  so could run a wire from pin 10 to dash light in with the link .

[western]

That would work 

[ballcock]

Personally I would wire them separately  as rears should only work with dipped beam where as being able to use the front with sidelights can be beneficial if the dipped reflect off the fog.

[miketomcat]

Depending on the age of the truck the rear fog light may have to extinguish automatically when the headlights are turned off as well as only work when they are on. This means a latching relay and momentarily switch.

Mike

[DaveSIIA]

Perfectly feasible. Our VW's (car & van) are wired so that the front comes on first and the rear at the second switch position. Rear has indicator light on the dash. Neither vehicle extinguishes the rear fog light when headlights are turned off.

[miketomcat]

45 minutes ago, DaveSIIA said:

 Neither vehicle extinguishes the rear fog light when headlights are turned off.

I'm surprised by this as it's been part of the IVA for several years. I guess either your VW's are old enough to not have this feature or there is some kind of exemption.

Mike

[DaveSIIA]

1 hour ago, miketomcat said:

I'm surprised by this as it's been part of the IVA for several years. I guess either your VW's are old enough to not have this feature or there is some kind of exemption.

Mike

62 & 63 plates on the vehicles. Just accepted that this is the way they have been from new and never had to look at IVA reg's - interesting. On both vehicles, the rear fog will work with side lights illuminated (bearing in mind that the front fogs will illuminate on side lights and by default will be on before the rear fog illuminates).

[Gazzar]

4 hours ago, miketomcat said:

I'm surprised by this as it's been part of the IVA for several years. I guess either your VW's are old enough to not have this feature or there is some kind of exemption.

Mike

My 109 failed the MOT because the fog light went out when main beam went on.

The operation of the lamp was interfered by the operation of another lamp.

I changed MOT stations and all is well.

[Snagger]

15 hours ago, ballcock said:

Personally I would wire them separately  as rears should only work with dipped beam where as being able to use the front with sidelights can be beneficial if the dipped reflect off the fog.

That used to be the case, but not for a long time now.  Whether the new rule is retrospective, I don’t know, but try a car built in the last 15 years or so and you’ll find the fog light operable irrespective of the dip switch selection.  Front fog lights don’t even need to have the headlights switched on at all.

[Snagger]

1 hour ago, Gazzar said:

My 109 failed the MOT because the fog light went out when main beam went on.

The operation of the lamp was interfered by the operation of another lamp.

I changed MOT stations and all is well.

That was certainly how things had to be in the 70s and 80s - the SIII fog light switch was spurred from the dimmed headlight circuit.  Mine still is, but I may update it by spring to the dash switch feed to the column.  Not sure there is much point though, seeing as conditions that need rear fog lights tend to preclude main beam - the old logic still seems sound.  Likewise the logic Saab and Volvo used on their lighting being all on whenever the engine is running, rather than these awful DRLs that make people think their lights are on at night but merely blind oncoming traffic while leaving rear lights off.  That’s real EU legislative logic there...
 

[ballcock]

3 hours ago, Snagger said:

That used to be the case, but not for a long time now.  Whether the new rule is retrospective, I don’t know, but try a car built in the last 15 years or so and you’ll find the fog light operable irrespective of the dip switch selection.  Front fog lights don’t even need to have the headlights switched on at all.

That was the point I was making about the front fog lights that they could be used with sidelights only when even dipped beam reflects off the fog. Rear fog lights I thought were still only to operate with dipped beam but I am an old git.

[ianmayco68]

20 hours ago, ballcock said:

Personally I would wire them separately  as rears should only work with dipped beam where as being able to use the front with sidelights can be beneficial if the dipped reflect off the fog.

I think you can with the off-on -on carling switch as the 2 on positions have activating separate feeds , so it's like 2 switches in one but first on only that works , second on both work .

[Snagger]

11 hours ago, ianmayco68 said:

I think you can with the off-on -on carling switch as the 2 on positions have activating separate feeds , so it's like 2 switches in one but first on only that works , second on both work .

The trouble with that is that you’d need the rear light output to go through a relay controlled by the main headlight switch output (not dim/main on the column, just headlights on generally) so that the rear fog can only be on with headlights - if you ran the feed for that switch from the main switch output, then the front fogs would also need the headlights on (not unreasonable).  Carling Tech Condura switches are rated at 20a, so would happily take the 4a for twin rear fog lamps and I suspect about 10a for a pair of front fog lights in their stride without relays.

[pat_pending]

Surely from a practical point, you'd want them switched separately?

In fog/snow you want the fronts on for forward visibility and the rears off to avoid dazzling following vehicles.

[ianmayco68]

I have also got front spot lights so if I need some extra lights I can put them on. It’s on the project and that has six surrounds so I’ve got a spot there , and the lights in the bumper are a pair, one fog and one spot light so the front fog would only be needed when foggy.

[LiamC]

23 hours ago, Snagger said:

these awful DRLs that make people think their lights are on at night but merely blind oncoming traffic while leaving rear lights off.  That’s real EU legislative logic there...
 

I see this all the time on the way to work in the early mornings when its still dark. It's quite dangerous on an unlit fast A road with no rear lights showing.

I was driving in the fog the other day (during daylight) and the problem was much worse, most of the traffic only had DRLs on (no rear lights at all). I assume that the automatic headlights detect that it's daytime but don't know that visibility is poor and people are so used to their lights being automated that they don't think to check what lights they are using?

[Snagger]

My 2014 Volvo has automatic lights switching, but it’s very unreliable and we use manual switching.  You’re right that is doesn’t sense weather, either fog or rain (or dust here).  But the idiots at the garage keep reactivating the auto function each service.  The problem with it is not the lights being turned on unnecessarily- the problem is that it often fails to turn the lights on at dusk and overrides manual selection of the lights on, so we move the switch on but the system keeps them off.  It’s outrageously dangerous.  Volvos old system was simple, logical and very safe; EU legislation screwed that up.

[cackshifter]

22 hours ago, LiamC said:

I see this all the time on the way to work in the early mornings when its still dark. It's quite dangerous on an unlit fast A road with no rear lights showing.

I was driving in the fog the other day (during daylight) and the problem was much worse, most of the traffic only had DRLs on (no rear lights at all). I assume that the automatic headlights detect that it's daytime but don't know that visibility is poor and people are so used to their lights being automated that they don't think to check what lights they are using?

And especially dangerous now there is a fair proportion with DRLs - it's possible for an unlight older vehicle to be concealed amongst them when the daylight levels are low

[Mo Murphy]

The problem is not the DRLs but the people driving cars, not using correct lighting for the road conditions.

As a driver of emergency vehicles, DRLs help me to see vehicles in shade in summer sunlight or winter gloom much more quickly meaning that I have more time to assess hazards as I approach them at speed in emergency conditions.

DRLs get my vote. People not being adequately lit don't .

Mo

[Bowie69]

Agreed, Mo, number of times you see people running around with just their DRLs on after sunset is astonishing. 

It doesn't help that most modern dashboards don't require backlighting once they went digital.

[jason110]

On the subject of headlights; the number of idiots folk driving around with poorly setup dipped lights really boils my p***

[western]

or one head or tail light out,

following a local police car the other day along from town towards my turn, the car had  the right brake light dead, the left & hi level were still working, so someone didn't check the lights before using the car,

if it had been one of my lights I'm sure I'd have got a ticket in seconds.