Fog lights MOT

[Jim GM4DHJ ...]

Is it OK for rear fog lights to go off when the ignition is turned off?....

[Brian Reay]

Yes.

They should only be used on certain types of road (plus other conditions), not for example in towns etc. Therefore you don't need them when the engine is off!

[NY]

Is there actually any prohibition from using them on certain types of road. I though the only rule was the obvious one of "turn off rear fog lights when the following car is so close that it will be dazzled by them"? I tend to keep my rear fog lights on in fog if I can't see any lights behind me, and turn them off when I can see the headlights of the car behind (on the grounds that when I can see him, he is probably close enough to be dazzled by my fog lights).

Embarrassingly, I spent the whole of one journey religiously turning what I thought were my fog lights off and on depending on whether I could see anything behind me, only to discover at the end of my journey that I'd been turning on/off the adjacent switch - for my heated rear window ;-) That was on an old Mark II Golf where there were three rocker switches on the dashboard - one for fog lights, one for heated rear window and one for something else - unlike the modern trend of putting the fog light switches as a pull-out on the on-dashboard light switch (modern VWs) or as a collar on the light-switch stalk (most other cars I've driven).

[Robin]

Why not in towns? I can't see anything in the Regulations or HC that distinguishes them from any other location.

[Marland]

I don?t if it has been made a regulation but it does seem the normal arrangement on more modern vehicles. It has certainly cut down on the number of cars seen with a rear fog lamp still on some time after conditions needed them. It wasn?t unusual to see a car being driven weeks or even months after the last time the lamp was needed ,now on a more up to date vehicle the effect of such forgetfulness* will only last till next time the vehicle is shut down.

• or unawareness and ignorance of the extra warning light showing somewhere on the dashboard for weeks.

I think the longest I went with one on was for about two miles on a Ford Escort where the light was put somewhere as an afterthought as it was designed in originally on that model a MK2 I think it was.

It had been turned on by the MOT tester and not turned off, subsequently I always checked and found the same after a couple of MOT tests. It was almost as if they did that as some sort deliberate party trick.

GH

[Brian Reay]

Oh dear....

[NY]

I've not come across any cars which reset the state of the foglights when the engine is switched off.

I have come across cars which reset it when the side light switch is turned off - sometimes as a mechanical interlock in the switch - which achieves the same purpose: that it is impossible for the foglights to come on (without deliberate human action) next time the lights are turned on.

I think I'd spot the foglight reminder lamp when I did my "cockpit drill" every time I start the car - scan the dashboard for unexpected lights, check for fuel level, check that oil and ignition lights *do* come on when the ignition switch is turned on and go out when the engine is running, etc. But I'm probably unusual in doing that quick check - and the old waggle of the gear lever before starting, to prove to myself that it's in neutral, which saves the car lurching forwards if I've left it in gear.

But I know what you mean about lights in inaccessible places. The worst was on my mum's old Renault 14 where the temperature gauge and warning light were on the centre console in front of the gear lever - not the sort of place that you routinely scan with your eyes while driving. My sister knackered the engine when a radiator hose blew and the temperature went sky-high... but she didn't see the gauge/light. Mum was not pleased, but she agreed that it was a very understandable thing to miss.

[NY]

Rather than tutting, perhaps you'd like to point me to the exact regulations. OK, so I omitted to say "only use them when it's foggy", because I thought that was blindingly obvious, though many people seem to use them even when it's completely clear (not even light mist).

Is there something in the highway code about classes of road or its speed limit which regulates when they may or may not be used, despite thick fog, subject always to the "don't dazzle" rule.

[Dave Plowman (News)]

They are very useful in daytime heavy rain too. Anywhere where they can be seen before the actual car itself on normal tail lights.

[Jim GM4DHJ ...]

excuse brian it is just the way he is ......

[Brian Gaff (Sofa]

Imagine you are the designer of this logic. It must be a nightmare. I'm sure there is some logic to all of this, but it passes me by. All I know is that rear fog lights can dazzle the following drivers. Brian

[ARW]

I have 10 plate van that turns the fog lights off with the ignition (but will start up with the headlight on) and a 62 plate car that I have no idea what happens with them as I have never used them other than to check the lamps work.

[polygonum_on_google]

Anyone ever fully understood why we only have one high intensity rear fog lamp?

[mm0fmf]

Two rear fogs on my car, and two on the one before it.

[Jim GM4DHJ ...]

got two other cars with only one....not a problem

[NY]

This has always puzzled me. Tail lights are at the extremities of your vehicle so as to define its width to a vehicle that is approaching from behind so it can judge how far away it is from you. In fog, tail lights cannot be seen from very far away, so rear fog lights serve the same purpose. So there need to be two of them, co-located with the tail lights.

But no, most cars only have one, on the offside. On my previous (older) cars, there was a bulb holder and red housing on the nearside, wired in. All it needed was to put a bulb in there and I had two foglights. But my present car only has a red housing on the offside (for a fog light) and only has a white housing on the nearside (for a reversing light). It's not just a case of fitting missing bulbs to give two foglights and two reversing lights.

When I'm reversing into a narrow opening between two gateposts, it is very useful to have reversing lights on *both* sides, so they light up *both* gateposts. In the absence of two reversing lights, I usually put on my rear foglight as a (red) reversing light to light the offside.

[Dave Liquorice]

Cheap car, probably only has one reversing light. Save two bulbs and positions in the clusters...

[mm0fmf]

On my eighth car since 1991, all of them switch off rear (and front) fogs when the ignition is switched off. Last car that had a toggle (latching switch) was an 1984 Open Manta GT/E.

Current and previous car have automatic headlights and pressing the front or rear fogs will cause the headlights to come one if they are off. I haven't tried with the headlights in manual to see how the fogs work. No point have automatic headlights if you don't use them.

Current car has lights in the instrument cluster for fogs. Previous had lights in the switches. But when the steering wheel was in the best position for me, the fog switches and light switches were obscured. You couldn't see if the fogs were on without moving about to see past the wheel. They switched off anyway so poor attention meant they weren't on for days.

My pickup has a mechanical interlock on rear fogs. You need headlamps on for rear fog and switching off headlamps also switches off fogs. Leaving the lights on and removing the key starts the bongs and beeps of doom.

[Dave Liquorice]

foglights

Mines does, and the previous two (but they were both Disco II's). Not sure if M reg Mondeo before them did.

Not tried that. B-) Hopefully you can turn the headlights off and retain the front driving lights. Have to do that fairly often coming over the tops in hill fog, too much bounce back from dipped headlights to have them on.

B-) I like mine but even though switching the car off resets the state of the fog and driving lights to off it doesn't reset main to dipped. So when they automatically come on next time they can come on in main beam. As I'm almost invariable on main beam when I arrive home at night, I have to remember to manually cancel that. Automatic things are good, provided they get it right...

[polygonum_on_google]

Completely agreed.

Two reversing lights should be standard.

Also, when switching to LHD countries, the HIRF is on the wrong side.

Sometimes, even if there are two sockets for HIRF, actually fitting a second one will trigger the light failure/checking - it will see too much current and report as a fault.