Any Thought's?

[Gagakev]

Had the van serviced today and the engineer changed the 's' plug, it had melted the centre pin.
Any one have any thoughts as to why this happened?
Would it have been over loaded somehow?
Could it be the lead/wire was loose and kept arching out?
Is this the plug that connects the fridge?

 

[colin-yorkshire1]

hi Kev,
could be a short, but as it is pin7 (fridge earth) that has melted and not pin 6 (fridge power wire) I would think it is an earth problem, or the wire to pin 6 would have melted as well.

 

[Sproket]

You are quite lucky it could have been worse.....
A bad connection creates heat & a possibilty of fire

I would swap the whole lot to a 13pin set up ......

it's a lot better connection & once that you have got the knack of plugging it in you will wonder why you have not done this a long time ago.......

 

[Damian]

A very common problem with the two 7 pin setup.
The centre pin on the 12s is the fridge return , and is the longest pin in the plug, which acts a guide, or king pin, when plugging into the socket.
Because the plugs are a tight fit, just about everyone wiggles them to get them in securely, which closes up the centre pin (there are two cross cuts in the tip of the pin), this reduces the contact area of the pin and creates heat when using the fridge whilst towing, and the consequential damage as shown in the pic.

Before each hook up, use a small flat bladed screwdriver to ensure the centre pin slots are not closed up, but take care not to over open them as the brass will break off..

Better still, change to 13 pin electrics.

 

[MichaelE]

Yes it is a very common problem, as Damian has already pointed out this is the fridge return/ earth and as fridges have more power dependant over the year and coupled with the bad pin connection problem this is a common occurance.
You can fit a mod which is putting a cable link between pin 7 and pin 3 in the plug to spread the earth return so not so dependant on the 1 pin.
Use the same gauge wire as the cable itself.

 

[Gagakev]

Brilliant thanks for the replies folks.

So think I will go for the 13 pin one.
Now a few questions.
1. When I had the tow bar fitted with the twin plugs The fitter said " it is also wired for the 13 pin set up when you changeover"
now I fail to see how this would work, is it possible? which plug would I use --presume the black one?
2. Would it be best to join the exististing two caravan cables back under the van?
3.would I get a wiring diagram with the new lead/plug if not any one got a link?

 

[Damian]

I expect what the fitter meant was that you have a fully wired system at present, including the fridge and battery charging.
To change , all you need to do is after disconnecting your car battery, rewire the 12N socket to the 13 pin socket floowing the same pin numbers, 1 to 7, after that, rewire the 12S substituting the colours in the fitted wire to the pins in the link.

http://www.sargentltd.co.uk/ISO11446_Data.pdf

So, Pin 8 =Yellow, Pin 9 =Green, Pin 10=Red, Pin 11=Black, Pin 12=Brown (but not used), Pin 13=White

 

[Dustydog]

Hi Kev

I had the same problem annually until I did this recommended fix. Never looked back.
http://www.towitall.co.uk/faq/1.aspx

 

[SteveP]

Hi, loked at this threads and thought brilliant tip, i have suffered this before. I have done the mods as per Michaels post, wiring 7&3 and have come back to the thread and seen Dusty Dogs attatchment, which offers a totally different wiring option!
I am now totally confused.com????

is either/ or correct?

 

[Gagakev]

Hi, loked at this threads and thought brilliant tip, i have suffered this before. I have done the mods as per Michaels post, wiring 7&3 and have come back to the thread and seen Dusty Dogs attatchment, which offers a totally different wiring option!
I am now totally confused.com????

is either/ or correct?

Good Post Steve, and I thought I was going bonkers

As pin 5 is unused, it is possible to link pin 7 to pin 5 and (provided the brown wire is earthed in the towing vehicle) share the load between both. ( Copied from link)

How do you tell if the brown is earthed to the vehicle?

 

[SteveP]

Hi Gagakev, ive checked the socket on the car and pin 5 will not give me an earth on the multimeter (thats how i think you would confirm/), but pins 7&3 will!

 

[MichaelE]

Use a electrical test meter set to continuity test and hold 1 lead to pin 5 and the other lead to the chassis of the car if it beeps then all ok

 

[Dustydog]

Oh dear Boys

You've missed the point

Pin 5 Brown is redundant in the normal course of things and NOT connected at all. On the car, towing vehicle connect pin 5 Brown to a healthy earth point.
This will now give you two healthy earths pin 7 Black and pin5 Brown. Make sure both on the car are linked to a good earth point. Do the mod as described on my previous post and Bingo

 

[SteveP]

Thanks Dustydog, i now understand that

Now my question is, i have connected 7&3 (both earths, i believe) this should also do the job?

 

[Gagakev]

Oh dear Boys

You've missed the point

Pin 5 Brown is redundant in the normal course of things and NOT connected at all. On the car, towing vehicle connect pin 5 Brown to a healthy earth point.
This will now give you two healthy earths pin 7 Black and pin5 Brown. Make sure both on the car are linked to a good earth point. Do the mod as described on my previous post and Bingo

Ah---plain english thats what a thicko needed

Thanks again chaps

 

[colin-yorkshire1]

that is correct steve, all you are doing is spliting the earth wire to reduce the resistance, in theory there nothing wrong with wiring both pins 3 & pin 5 to pin 7, after you have connected the brown wire at the car end to earth. of course.
personally I would go down the 13pin route, it gives you more options and is not that difficult I did both the car and van in one afternoon.

 

[MichaelE]

As pin 5 is not connected and presuming you have a free cable in the flex you will have to cut back the flex remake the plug and remake the other end to the earth of the car you might as well fit the 13 pin socket as its as much work? , as a fix which works and much quicker to do fit the link pins 3 & 7 as you are still splitting the earth

 

[SteveP]

Thanks lads

 

[Guest]

As most 'professional' towbar fitters use prewired sockets, it's probably only the end they are meant to fit that is left disconnected, least this is what I found so it was just a case of connecting the brown wire to the body of the car.
BTW, it is not a case of halving the resistance by using two pins as the resistance is an unknown, what is known is the constant load for the fridge is 10amps. By then sharing this between 2 pins you are sharing the amperage to a more manageable 5amp per pin, should one or both pins have a high resistance

 

[colin-yorkshire1]

BTW, it is not a case of halving the resistance by using two pins as the resistance is an unknown, what is known is the constant load for the fridge is 10amps. By then sharing this between 2 pins you are sharing the amperage to a more manageable 5amp per pin, should one or both pins have a high resistance

hi gary, sorry mate that statement is not strictly true, while the current load of the fridge circuit is contant at 10amps, via pin 6 in order for the circuit to work it has to return via the earth wire pin 7,
as Damian explained earlier pin 7 is a kig pin it is slightly longer and therefore more prone to wear this makes the pin slack increasing the resistance and allowing arcing of the contacts it is this that burns out the plug, (Humphry Davy circa 1800) adding a extra earth contact, while reducing the resistance it does not half the amps to each pin, merely spreads the load, to pervent arcing in extreem cases after the modification most of the current could be carried by pin 3 alone, while the mod may work for a long time it is only ever a bodge as the brown wire to pin 3 is often only 1.5mm and not 2.5mm that the earth wires are.
the best solution is to change over to a 13 pin fully wired set up.

 

[Dustydog]

In addition to my earlier post I do agree the stainless steel 13 pin is by far the best but my plagiarised mod has stood the test of time. It is worth cleaning both the plugs and sockets with electrical contact spray, then reopening the pins as Damian said. Do not use WD40.

 

[Guest]

BTW, it is not a case
of halving the resistance by using two pins as the resistance is an unknown
variable, what is known is the constant load for the fridge is 10amps. By then sharing
this between 2 pins you are sharing the potential amperage, (assuming initially
both being new so making good contact), to a more manageable 5amp per pin, Should
one pin later develop a higher resistance, then the other will automatically take
up the slack as current always uses the
path of least resistance.
Well Colin, I’ve edited
it from the 1am version of this morning, hopefully this puts my thoughts over a
bit better? But, I did a lot of playing around to get the best performance from
my fridge connected to the last Mondeo before it worked as it should. Basically
I fully wired the brown wire both in the car and van to provide another full
earth return, therefore increasing cross section of cabling substantially and
all but eliminating voltage drop.
The wiring Ford supply
on my latest Mondeo is totally inadequate to run the fridge efficiently, that’s
regardless of it being fitted with a 13pin socket, so luckily before I started
all over again, Metz who comes on here from time to time summed it up for me?.
What he said is, he
drives from home in Skegness with a stocked pre-cooled fridge to somewhere in
France before his first stop over, here he finds the beer is still acceptably
cold without the fridge having being switched on sapping engine power hence
fuel on the journey?!

Of course then you
could spend money converting to the far better 13pin system, or leave as is
with fridge switched off and perhaps spend the savings on beer!
Personally having 13pin
socket fitted already, I’ve bought a 13pin to 12N adaptor socket and left the
van as it is!

 

[colin-yorkshire1]

hi gary,
thanks for the amendment,

much better

. my apologies for being so precise, but electricals are a particular passion of mine. you may have gathered that already due to the number of postings I make on the subject,
the almost magical properties some people impart on it are, well suprising!!. when in fact the mechanics of electrical current are quite simple,
that aside, the 2 main elements of grey plug overheating, are resistance and arcing, the modification spoke of will reduce the occurance of plug overheating, due to quote "Should
one pin later develop a higher resistance, then the other will automatically take
up the slack as current always uses the
path of least resistance. " it should also be noted that it is better to attach the earth wires at different points on the car so if one earth contact becomes unstable, the other would carry the load,

 

[Gagakev]

Decided to go down the 13 pin plug route, arrrived last week but didnt have time to fit it
So go to hitch up last Thursday and guess what the socket on the car had melted as well so the new plug wouldnt fit

So just a quick question on the wiring it says in the chart below that pins 7 and 3 are earth pins are they already connected ?

Wiring chart

 

[colin-yorkshire1]

yes they should be!! Kev because both earth wires are on a closed circuit one for the fridge and the other for the charge circuit,
the other earth wire "the white one" serves pin 1 to 8 so when you change the car socket check the earths there should be 3 connected to the car body.