7 Pin 12n Adaptation To Accommodate Reversing Lights?

[clarkey1984]

Hi all, first of all, I know that if I do this then my cars socket will only work properly with my caravan and trailer that I will mod to suit, but what I basically wanted to do was to use just one of the sidelight connections for both of the rear lights, which would then give me a spare wire that I could use for a reversing light, as according to what I can find online the trailer I am in the process of rebuilding should have a reversing light, and this seems like an easy way to achieve it with the 7 pin single plug system I have, I'm going to be running all LED bulbs with both the caravan and this trailer once its done so I don't think that the extra load from 3 more bulbs on one circuit should be an issue, has anyone done anything similar before?

 

Many thanks in advance:)

[Stevan]

Before the widespread adoption of the 12S socket there were quite a few variations of the 12N wiring, such as you suggest, both for reversing lights and/or battery charging and fridge. Using LEDs to limit current consumption will certainly help avoid overloading the connections.

 

When buying a 2nd hand van mismatched wiring was a common problem!

[clarkey1984]

Just what I was hoping to hear, I've already got some 5w capless LED bulbs for the front corner/side markers but will order 4 ba15d LEDs so I can do my 1990 abbey 516gt as well as the trailer.

 

In honesty it would have probably been a lot easier to just buy a ready done trailer lighting kit, but I have had these mk2 ford Granada rear clusters for absolutely years and always wanted to use them for something, no backing plates and thus no bulb holder or wiring as they were lost years ago but the individual bulb holders are pennies off the internet so I've got more than enough, I made the mini loom up on the back of each light yesterday but all it needs is one wire adding in and a bulb holder.

 

Annoyingly the fog light in the cluster is on the near side so incorrect, the other cluster has the hole blanked off, in that case then the ns reversing light will remain as a reversing light and the offside one will have a red bulb fitted and become the fog light.

Edited June 10, 2017 by clarkey1984

[Woodentop]

Regret to advise that Stevan's advice is incorrect. There was no variation in 12N pinouts in the past. Up to the end of September 1979 the blue wire on pin 2 was a permanent 12V from the car to provide 12V if there was no caravan battery, or to charge the battery if there was.

 

From 1/10/79 a rear fog light became compulsory on all new vans including yours so pin 2 was reallocated as rear fog and the 12S socket came into being. That means that your caravan should have 12N and 12S - you don't specify.

 

It is actually much easier to fit a 12S and the wiring than to make the 12N non-standard especially with a car the age of yours.

 

There is no requirement for a reversing light to be fitted on a caravan - not that it would be of much good to you anyway.

[Stevan]

Regret to advise that Stevan's advice is incorrect. There was no variation in 12N pinouts in the past. Up to the end of September 1979 the blue wire on pin 2 was a permanent 12V from the car to provide 12V if there was no caravan battery, or to charge the battery if there was.

 

From 1/10/79 a rear fog light became compulsory on all new vans including yours so pin 2 was reallocated as rear fog and the 12S socket came into being. That means that your caravan should have 12N and 12S - you don't specify.

 

It is actually much easier to fit a 12S and the wiring than to make the 12N non-standard especially with a car the age of yours.

 

There is no requirement for a reversing light to be fitted on a caravan - not that it would be of much good to you anyway.

Wrong on two counts!

 

Although there may have been only a limited number of official variations of the 12N plug wiring, there were many unofficial variations. I bought two caravans and one car with them! And sorting them out was not easy, requiring a "Start from scratch" approach.

 

As to reversing lights not being "much good" on a caravan, the need to warn people that you are reversing is far more important on a caravan (with limited rearwards visibility) than on a car!

[Keefmac]

It's funny, I just mentioned reversing lights the other day on my B+E course (on trailer light check).

 

Both instructors said reverse lights where not needed because you should never revers on the road as you don't know what's behind you.

 

I can see on site they are valuable but seems not a legal requirement for road use. .

[RADIOTWO]

Hi all, first of all, I know that if I do this then my cars socket will only work properly with my caravan and trailer that I will mod to suit, but what I basically wanted to do was to use just one of the sidelight connections for both of the rear lights, which would then give me a spare wire that I could use for a reversing light, as according to what I can find online the trailer I am in the process of rebuilding should have a reversing light, and this seems like an easy way to achieve it with the 7 pin single plug system I have, I'm going to be running all LED bulbs with both the caravan and this trailer once its done so I don't think that the extra load from 3 more bulbs on one circuit should be an issue, has anyone done anything similar before?

 

Many thanks in advance:)

Why don't you just use a 13 pin plug/socket then you have the scope if you need a charging circuit

[Rodders53]

Biggest issue with non standard wiring is recovery of a breakdown by a third party with a standard wired socket.

 

Much better imho, to fit 13 pin, and wire the caravan lights to the correct pins?

[ReggiePerrin]

Biggest issue with non standard wiring is recovery of a breakdown by a third party with a standard wired socket.

Much better imho, to fit 13 pin, and wire the caravan lights to the correct pins?

Indeed. .. but it might be worth pointing out that a 13 pin socket is an MoT pass or fail item so any bodgery (customisation) there is not such a good plan.

[Stevan]

Of course, you could just fit a 12S socket and plug but only connect the functions you need!

[Guest]

I know that if I do this then my cars socket will only work properly with my caravan and trailer that I will mod to suit,

Thereby is the problem should you wish ever to tow another trailer, or your caravan be towed by a different vehicle - maybe if being recovered if your car breaks down?

Of course, you could just fit a 12S socket and plug but only connect the functions you need!

Also leave the 12N connections in standard configuration. The two wires allocated to the side lights on the 12N configuration is in fact intended as a safety feature that will keep at least one rear light working in the event of a supply failure or wire breakage.

 

Clarkey1984, I would advise you to leave the 12N in standard form, and add a 12S to accommodate and additional functions such as the reversing lamp. The alternative would be to fit the new(ish) 13pin connection and accept that this will then become part of the MOT testing for your towcar.

 

Gordon.

[clarkey1984]

Very good points guys, I was going to adapt the single plug and socket purely because I already have them, the 2nd socket however makes a lot of sense for the reasons stated, thanks to you all

[philspot]

On the theme of number of pins, I'm sure I had a trailer plug from my father that had just 5 pins - presumably for:

 

Earth return

Lights

Indicator L

Indicator R

Brake

(in any order)

Does anyone remember these? (Could be from the 1950's)

[Guest]

On the theme of number of pins, I'm sure I had a trailer plug from my father that had just 5 pins - presumably for:

 

Earth return

Lights

Indicator L

Indicator R

Brake

(in any order)

Does anyone remember these? (Could be from the 1950's)

Yes that was true before the standard wiring of the 12N (7 pin) was agreed (IIR around the time that rear foglamps were fitted to cars as standard).

There was also a variation of the 12N socket that permitted the rear fog lamps of the towing vehicle to be interrupted if a trailer was attached (to prevent reflected shine from the front of the trailer) although this required eight wires in the towcar to operate and a small switch was installed within the socket and operated by insertion of a plug, the pin connections remained compatible with all trailers of the time.

Gordon

[clarkey1984]

Most definitely going to go for the 12s option as it opens up so many more possibilities in regards to the fridge etc on my caravan, plus also solves this problem of reversing lights too, the only non standard thing I am going to do however is ditch the white earth cable in the 7 core cable and instead run a nice thick (probably 10 gauge) cable from the existing plugs earth connection as far as I need to and bolt it to the a frame, and then do the same from each light to the frame using the same cable, I'll also do the same to the socket on the car and fix it to the body in the same way, because as things are I'm getting a slight flickering of the rest of the lights when the indicators are on, which normally indicates an earth problem, made worse when the brake light are on, there can't be an earth problem as such as everything is new, other than the cable itself not being big enough to return all that current when everything is on together, and as my car has daylight running lights which you can't turn off, this is a worthwhile upgrade I think.