Message Forums

sounds like a fault on your cars wiring.old wire plan.

found this

How can I test both the 12S and the 12N Socket?

by David Thorber

To test both caravan connection sockets, you need to arm yourself with a 12 volt bulb with hook-up leads. One of those 12 volt electrical test screwdrivers is ideal. If the crocodile clip won't reach far enough into the socket to make contact, simply clip a bent paper-clip into the jaws.

On both 12N and 12S sockets, pins 1 to 6 are numbered clockwise from the top (pin 1 = 12 o'clock, pin 2 = 2 o'clock... pin 6 = 10 o'clock.) Pin 7 is the centre pin. (See the following photos)

Footnotes:
[1] If the vehicle has only ever towed small trailers, then the original owner may not have bothered with the rear fog connection. This is highly unlikely if you also have the 12S socket. If this is the case though, you do need to get this rectified before towing a caravan.
[2] Many people don't bother to wire up the reversing lights, so don't be surprised if these don't work! It's up to you whether you get them fixed, and as far as I'm aware, they're not legally required.
[3] A new method of battery charging wiring means that pin 2 on the 12S may not operate as described (i.e. it's always 'dead.') If this is the case, then you will probably be perfectly fine with a modern (late 1998 onwards) caravan but will need to get this resolved if you want to charge the battery in an older model.
[4] Depending on how the switched supply is sourced, you may or may not get a reading from 12S pins 2-3 and 6-3 with the ignition on but the engine not running.
[5] This tests that there is a ground connection on pin 7 - required for caravans produced after mid 1999. Without this connection, the fridges in these late model caravans will not run off 12 volts. For older caravans, this is not required.

As far as reversing and fog lights are concerned, I've always beleived that, if a light is fitted, it has to work.

Jim

hi there we had a similar problem to this and turned out to be that when someone(me) screwed the number plate on i had gone through the cable for the back lights giving a short circuit

good luck with it!!!!!