Tow Bar Electrics 7 or 13 pin plug

Is there any legal prohibition in having two fog lights? Is it mandatory or option for manufacturers to fit just one fog light?

A lot could be improved if the design of light clusters was improved to space out important lights (eg tail and fog in one cluster, indicator in another, brake in a third, with enough dark space between each that you can see all the lights that are lit. Some of the recent Marks of VW Golf are terrible because the brake light is a ring that surrounds the indicator, and the brightness of the brake light obscures the indicator light until you get close. Likewise for the font indicator which is so close to the headlights that you don't see it as easily. We may laugh at American cars of the 1950s which had a series of indicator lights which were illuminated in sequence, but you can't deny that they were very visible:

No. Only Dennis's Lada has one. And they are supplementary to brake lights to try and help idiots confusing them with brake lights.

NY formulated the question :

Vehicles are wired with two circuits, that is for safety, should one circuit side fail. My cars intelligent trailer lighting system, uses a fancy unit which obtains all of its supplies from a single source, which rather defeats the onject of having separate circuits for left and right. It constantly monitors the trailer circuits for lighting faults and disables the cars rear fog when a trailer is attached, plus other items.

I can see the problem with brake lights and fog lights being confused. In fog, you start to see a pair of red lights out of the gloom. They may either be fog lights on a car that is moving at about the same speed as you in the same direction (in which case you think "car ahead of me, thanks for the warning, may need to slow to his speed") or else they may be brake lights (with no fog lights, and tail lights not yet visible) in which case you may need to stop, perhaps quickly. Obviously if you are in any way unsure, you treat them as brake lights, but that may lead to needless panic-braking. Of course if they are brake lights then almost certainly there will be a third, high-level brake light in between, but try sorting out two versus three in a split-second when you're using instinct and reflex, before your brain has processed the situation. That reflex-versus-rational thing applies in the same way to one fog light versus two (or three) brake lights.

Mind you, it's rare to get fog that is so thick that you only see a car's lights when you are already very close to it, so you usually get several seconds to slow down gradually and assess what sort of lights they are and therefore what action you need to take.

You can't always rely on two fog lights versus four lights (fog plus brake) because many considerate people turn off their rear fog lights once they can see the headlights of the car behind, to avoid dazzling him - and to make their brake lights show up better when it actually matters (if there's no-one behind me, it doesn't matter whether they can tell that I'm braking).

Embarrassing story: when I first got a new car (it was probably my Golf Mark

Seems remarkably daft to drive into traffic that you think is braking.

Why does that redundancy only apparently apply to the tail lights and not the brake lights - or at least both standards only have one pin for brake and one for fog, whereas they have two for tail. I'd have thought that redundant circuits in a car for brake lights might be useful as well, suggesting two pins (one per circuit) for brake lights.

I wonder if it does go back to earlier cars being able to switch on the tail/side lights on just one side when parking, to halve the battery load. Sound plausible. When did that go out of fashion? Odd that I've never noticed any cars since I started driving in the early 80s that were parked with just the offside lights lit. Maybe I have, and assumed that it was due to a blown bulb :-)

Interesting wiring/logic to achieve the indicator switch turning off the opposite tail lights. I presume the indicator switch had a second set of contacts which broke the relevant lighting circuit.

I've always wondered how the indicator mechanism managed to turn off the brake lights on one side of a car in the days when the same bulb was used both for brake and indicator, before separate bulbs (one showing orange) became mandatory. You need the brake light to come on permanently if the car is not indicating, but to be modulated on one side by the flashing circuit if the car is indicating. Dead easy with modern logic, but not so easy with relays.

Do any US states still permit flashing brake/side lights as indicators, or have they all gone over to flashing orange lights now to make a clearer distinction? As recently as the late 90s, when my sister was living in Boston, all American-made cars (even brand new ones such as my sister's Dodge) seemed to have flashing red lights, whereas all imported cars (such as VW Golfs and Hondas) seemed to have flashing orange. So both were permitted and neither one nor the other was mandatory.

When driving in fog you need to drive slowly enough to stop before hitting another vehicle even if you can't see any lights, perhaps because of an earlier accident.

Many people drive much to fast in fog. On the motorways they just assume that the road ahead is clear. The Sheppey bridge was recently blocked by a multiple vehicle accident in fog/low cloud.

My Touran could do it - you had to flick the indicator stalk one way or another *after* turning the ignition off. The MINI can do it but I forgot how. My Tucson: not sure - just off to read the manual!

It is still available on some modern cars. However, using it would be contrary to the UK Lighting Regulations.

NY formulated on Monday :

The original 12N 7 pin just had the basic essential road lighting circuits. The 12S added as a later upgrade to the 12N, had reversing light feed, plus fridge and battery charge, via a relay or voltage controlled relay, extra earth terminals and a reverse sensor/spare.

The 15pin replaces both 12N and 12S with a single socket and plug, which is supposedly more robust.

NY was thinking very hard :

If in any doubt, you react to the worst possible scenario.

NY formulated on Monday :

...and part of my 'post flight' is to make sure >I have left it in gear

I've seen some cars with two 7-pin connectors and I presumed that the second was for the things like permanently and switched live and reversing lights. What is odd is that my parents had our caravan (Lynton Javelin - how do I still remember that name) in the early 70s, I'm *sure* we only had one 7-pin socket and not a second one. OK, I was about 10 at the time, but I was at an age when anything "different" stuck in my mind. Maybe I've mis-remembered.

Do you mean 15- or 13-pin? Is there another third type of connector?

It happens that NY formulated :

I'm not sure when the 12S use began, but I don't think it was around in

Sorry, I mistyped it is of course a 13 pin.

They're separately fused on my Merc and my Transit.

Bill

Ours had a gas/electric fridge: gas when stationary, so as not to drain the car battery, and electric when moving, because the draught caused by the caravan moving at 40 mph (*) would blow out the gas flame.

It had both gas lights (with mantles), and 6" 12V fluorescent lights which made an infernal whistling that my sister and I could hear but my parents (being no longer in the first flush of youth) couldn't.

If the 12S connector hadn't yet been introduced, I wonder how switched 12V was conveyed to the fridge and I wonder if the 12N had an unofficial modification to use one of the two tail light pins for switched 12V, with both rear lights being fed from the other pin. Unless we always drove with the side lights on :-) I'm *sure* I only remember one 7-pin plug. Maybe there was some wholly non-standard connector for that one extra wire.

The one thing I don't remember was having to go through any elaborate levelling procedure so the fridge would work properly, with wedges under the wheels, whereas my wife who had a motor-caravan before I met her said that it was essential to jiggle the vehicle on wedges under each of its four wheels until it was level in two dimensions. We just shoved a bit of wood on the ground at each corner and lowered each jack until it pressed the wood against the ground but without actually lifting the caravan off the ground. As long as the caravan didn't rock, who cared if the floor sloped slightly. Were we lucky or did earlier gas fridges not need to be kept dead level when they were turned on? I do wonder whether a couple of screw threads operated by the jack handle, to tilt the fridge until it was level, might have been easier than having to raise some of the wheels by driving up ramps until the whole vehicle was level.

My parents sold the caravan in 1976 when they bought a holiday cottage in the Yorkshire Dales which they renovated each weekend and which they still have.

(*) I remember the excitement when the law was changed to allow caravans to go at up to 50 mph, providing the car's and caravan's weights were printed somewhere prominent on the caravan (grandpa hand-lettered it on the removable flap for the fridge burner), the caravan was no more than a certain proportion of the car's weight, and a "50" sticker (white lettering on a black disc) was displayed in the rear window of the caravan. These days I believe the limit has been raised to either 60 or 70 - with similar provisos about ratio of caravan to car weight.

Back in the seventies I doubt any caravan had reversing or fog lights so in theory in a 7 pin plug you could have earth, L indicator, R indicator, brake lights, sidelights and have two pins left over for ignition switched live and continuous live if you wanted.

Regarding fridges, it's always been my experience that being off level

Tim

That wasn't the reason. Until quite recently, it was illegal to operate gas appliances on the move. Now there are special 'drive safe' regulators and hoses which you can use with some appliances on the move. Some motorhomes have them so you can use the gas heaters while on the move. There is a sensor in the regulator which detects an impact and special sensors in the hoses to detect ruptures.

We rarely use our motorhome fridge on gas, modern ones tend to operate on mains/gas/12V, but it isn't quite that critical. We get the van level as much for things like cooking- frying eggs on a slope is no fun- as anything. May be the older ones were more sensitive.

As a kid who grew up caravanning I can add some authority to this:

I have seen people using these, but they were NOT universal - none of our, admittedly second hand caravans had them, and our 1976 car was only wired with 12N.

It's a sensible system - compact, all the features (and a spare pin) and the 13->12N adaptor is not very big, so you can still basically hang a