7 pin to 13 pin plug conversion

[saint-spoon]

Just a quickie techy team. How easy is it to change from a 7 pin socket over to a 13 pin, is it just a case of rewiring or do you need to run new wires to supply the caravan services? I am just wondering whwether or not to pay someone to do the job or to do it myself. if it's just a case of removing socket and putting a new one on then EPLS I'll do it myself but I have a sneaky suspicion that it is a bit more involved than that and lacking experience I should leave it to someone who does this for a living.

 

[Damian]

If your current sockets are wired correctly then it is a simple matter of swapping the wiring over to the 13 pin socket.
However you will probably have to identify the correct wires for pins 8 to 13 as the old grey cable may have the same colours as the black cable.

 

[saint-spoon]

I am looking at a couple of replacement vehicles for my crate of a terrano and a couple have just the single seven pin socket for towing a trailer so my question was about whether or not that could be swapped over to a 13 pin or would I need extra cables running.

 

[Damian]

The single socket will only give you road lights, you would need to run two fused 12v feeds, one from the car battery and one from a switched 12v supply to give you fridge and charging, along with two returns and also take a feed from the reversing light to the socket.
The two new feeds and returns must be in 2.5mm cabling.

 

[saint-spoon]

That sounds like leave it to the professionals to me... thank you for the help.

 

[Thingy]

You should have two 7 pin sockets, and there is an adaptor on the market, costs around a tenner for a cheap one , which takes your two sevens to one thirteen.

See this image

 

[DrZhivago]

True what Damian said, but it is also usual to put a voltage-sensing relay (sometimes called a splitter relay or smart relay) into the supplies to the caravan battery charging and fridge lines (cores 4 and 6) so their load is shed if the car alternator starts to struggle with all the load on it

http://www.towingelectrics.com/relays_caravan.php
http://www.ringautomotive.com/uk/products/Towing/Towing Electrics/Relays/RCT460
I find it ironic that the newer 13 pin socket has fewer cores than the old 12N+12S double socket set-up. There are no spare cores left in the 13 pin socket :-

http://www.caravanclub.co.uk/media/1022790/towbar-wiring-mo.pdf
You would have thought that a newer standard would have allowed for possible future expansion, and not repeat the mistake of the old 12N.

 

[wwwdot]

Funny enough I changed mine last night because I wasn't happy with the adapter same as pictured. Took me 2hrs in the rain. Had to take the tow ball off to change the mounting plate as they are different. Hole in plate is a lot bigger on the 13 pin. Otherwise a straight forward job

 

[Gafferbill]

........you need to be very careful here because the wiring on the towing vehicle can be different depending on the wiring on the caravan being towed.
The main reasons caravan wiring differs is due to the age of the caravan and what wiring standard was used when it was built.
Some advice already given in this tread would be incorrect for some ages of caravan.

 

[Martin_E]

One of these are excellent, no extra cables to drag down the road and they lock into place.

http://www.jacksonscamping.com/uk-short-adaptor-13-pin-12n-s-adaptor/p5998

 

[chrisn7]

[quote="

I find it ironic that the newer 13 pin socket has fewer cores than the old 12N+12S double socket set-up. There are no spare cores left in the 13 pin socket :-

http://www.caravanclub.co.uk/media/1022790/towbar-wiring-mo.pdf
.[/quote]

I don't know what the 'Sensing device' referred to in the CC description is, but pin 12 is normally unpopulated, so remains a spare?

 

[WoodlandsCamper]

I don't know what the 'Sensing device' referred to in the CC description is, but pin 12 is normally unpopulated, so remains a spare?

I believe if you link pin 12 to 12v in the caravan connector then the car can 'sense' this voltage and know a trailer has been connected. The car can then warn if the connector has been disconnected.

 

[DrZhivago]

chrisn7 wrote:-

I don't know what the 'Sensing device' referred to in the CC description is, but pin 12 is normally unpopulated, so remains a spare?

Section 3.5.16 of that CC fact sheet tells about the use of the "Sensing Device" core. It is to tell the car that a trailer is present (or not) for several possible reasons, the most visible of which is for the car to supress its high intensity rear lights. The car may or may not use this information though.

To this end, you may find that this core is earthed on the caravan side. You would in that case need to un-earth it to make some other use of it, but you would then need to be careful about what other cars connected to it.