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MG MGB Technical - Fog Lamp Switches

My 1976 roadster is fitted with front and rear spot/fog lamps, which I guess were either fitted as an extra when the car was new or by a PO in the last 40 odd years. The car went through its MOT yesterday with no problems, however the tester did mention that rear fog lights should have a warning light to show that the have been switched on. Both the front and rear spot/fog light switches look original to me (see photo).

Was there a requirement in the dark distant past for rear fog lights to have a warning light and are the switches a standard BL part for the period?

Thanks

Andy



Andy Robinson

Maybe not in the dark distant past, but they do have to have an indication now. Manually operated reversing lights have always needed an indication, from memory of the period when they first appeared as after-market accessories. Clausager specifically mentions a warning light for the HRW (obviously not an MOT requirement) either as a separate lamp or an illuminated switch, but makes no mention of a warning light for the factory fitted rear fogs on 1980 models.

However it need not be a warning light, it can just be a visible mark that is exposed when the switch is on:

"b. the presence and operation of the tell-tale. Note: Some tell-tales may be in the form of a coloured tag on a switch. "

http://www.ukmot.com/manual/1.3/Rear-Fog-Lamps

Ironic, really, as rocker and especially toggle switches are pretty obvious when they are on, and a blue (for example) tag is as 'visible' in the dark as the switch :o)

Can't comment on those switches except to say the logo is quite different from the main lighting switch on my 73 and 75.
paulh4

My late '79 didn't have rear fogs fitted. I fitted them but can't remember whether a tell-tale was necessary. Judging by the number of people who drive around on clear nights with their rears on, fronts as well, the warning lights should be at least 50watts!!
Allan Reeling

My 1980 roadster had rear fog lights factory fitted. The later style switch has a rectangular hole at the top of the rocker that gives out a yellow/ orange light when switched on. When I for a time added front foglights I used a similar type switch that filled the blank where the HRW light/switch is on the later GTS.
I know that it is not a requirement for the main headlight blue bulb indicator to be visible (as mine is only discernable at night) for cars registered before 1 April 1886.
Cheers, Charles
Charles9

Worth looking at the Road Vehicle Lighting Regulations 1989 archive. Front fog lights are described as optional with no tell tale light requirement!
Charles9

Thanks for that info Charles.

The main beam tell-tale probably isn't a fail going by my experience. I got an advisory for not having one on my V8. There was a bulb-holder hanging down as at the time I was experimenting with LEDs for the instruments and at that time had one with a different fitting. The V8 tell-tale is not a clear 'jewel' as on the roadster but only translucent, and the only time you can see it lit is in near pitch-black, I assume it is the same as yours, Charles.

Rear fogs are also optional before 1980, but must have a tell-tale of some kind. A single one must either be in the middle or the off-side, and if you have a pair the off-side one must work but the near-side may not. I forgot to check mine one year and the off-side one wasn't working, so he simply disconnected the near-side and passed it with a verbal comment :o)

It's supposed to be an offence to drive with front or rear fogs on unless the conditions warrant it.

The ZS is a weird one. The rear fogs are available with 'position markers' on only. Front fogs are the same as long as the rear fogs are on, but if they are not on then they are only available with the headlights. I say 'weird' but there is sense there. Both switches have an illuminated tell-tale.
paulh4

Some questions, Charles: I believe the rear fogs are only available with the headlights on, is that correct?

These switches are illuminated at night when the parking lights are on and the switch is off. Is it still illuminated with the panel lights are switched off with the parking lights on? Or do they go off as well?

Thanks.
paulh4

Having done some more research I have found that the spot/fog rocker switches were available for my car, but are NLA now. This is from the parts catalogue:

36 GAE140 Switch - Auxilliaries - Rocker . . . . . . . . A/R Fog and spot lamps etc.; GHN5, GHD5 - 258001 to Sept. 1976

It would seem that these switches never had an indicator fitted to them, so I would assume it was not a legal requirement to have them. To keep things original I can fit a LED indicator above the switch, or just buy a new switch with a built in LED. The main problem is getting a switch to fit the existing hole as I think the switch size changed after September 1976.

Andy
Andy Robinson

The switches changed significantly for the 77 model year on, being smaller, squarer, and having night-time illumination (as well as tell-tales in some cases).

There's loads of illuminated rockers switches around if you Google, you would have to research the sizes. Have you seen these? https://tinyurl.com/y94v2cva

The PO had rather butchered the area below the air vents on my V8 and had an assortment of switches. I was able to get a set of illuminated ones at Stoneleigh many years ago, slightly bigger than standard but at least they covered the odd holes when in an additional facia panel cut from textured black plastic - L-R cooling fan indicator and override, rear fogs, front fogs.

I avoid drilling holes whenever I can, to do so would take originality away, I suggest.



paulh4

On a 1980 LE two years ago, I picked up an advisory for the main beam tell tale light not being bright enough.I am pretty sure a non working main beam tell tale light would be an MOT fail.
C Harvey

And I meant to add that the switch for the rear fog lights has an orange tell tale light. Also the circuit is such that they will not function unless the headlights are on.
C Harvey

Hi Paul,
In answer to your questions:-
The rear fog lights only work when the headlights are on.
If i turn the panel lights off,nothing shows when i turn the fog light switch on when only the parking lights are on.
If i then put the headlights on & then the fog lights the fog light tell tail light comes on.
Further to my comment on the headlight blue warning light,some years ago, someone from the forum (apologies to who it was,but i can't recall who) drew my attention to the relevant section on headlamps at the time the MOT inspection regime was being beefed up about the requirement for tell tale/warning lights on the dash. (I had raised the issue for about that time my usual MOT man advised that the following year i would have to have a tell tail light that could be seen).
I downloaded the relevant section & ever since have placed it on the passenger seat when the car has its MOT. It has not been questioned since . (Incidently my car had its MOT yesterday & passed without any issues including a CO reading at idle of circa 3 so i am well chuffed)!
I will attach a copy of the relevant section although the hand written note is specific to my car.
Cheers
Charles
Charles9

Paul,
Here is the extract from the MOT inspection manual.
Charles


Charles9

Thanks for the info on the fog-light switch, Charles.
paulh4

Thanks for the link Paul. I have measured the existing switches and the switches in the link should fit the existing holes in the centre console. I wouldn't be able to fit switches where you have fitted yours as under the air vents a PO has fitted a vacuum gauge and a clock.

Andy
Andy Robinson

This thread was discussed between 16/05/2018 and 17/05/2018

MG MGB Technical index

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