I think it's a legal requirement to have the trailer dash light on with the trailer.

If you don't have the dash light working then you have to have an audible indication.

Most generic kits have a buzzer as it's cheap but I think though you just need a way of telling you when the trailer lights aren't working, the bulb check system should come up with a warning on the dash display if a trailer light fails i think.

An old Volvo i had, there was a red light that came on the dash if a bulb on the trailer failed, if it was all working there was nothing.

http://www.rightconnections.co.uk/rear-mounted-buzzer

I have genuine OEM parts fitted, all be it with Westfalia stickers, but they is genuine May be this turning the socket on is a 2005+ thing that Ford have introduced to get more dosh, My BMW is plug and play, and I thought that the later ones were too

IanT599, the 2002 - 2005 has neither audible warning or trailer light, and it is legal. I think that you'll find you have to have a way of telling if an indicator is NOT functioning. If my car detects a duff connection the Death Bong goes, along with the screen of Doom, and for good measure it also makes the indicators go rapid but I have no blinking trailer on the dash, and no annoying squawking from the rear of the car.
And why do you need sat nav to see if the trailer is connected? I just use the rear view mirror  Yesterday I couldn't spell Engineer... Today I are one!
Inventor of the 'Guide-o-Matic automatic wheel alignment tool'
Former long term L322 owner, Up/Down graded to a Classic Tractor!

I think he means by satnav on the later ones, you can tell it what sort of trailer you have so it can adjust the electronic stability program to match it. ie. if it's a big heavy horse box, it's going to affect the handling more than a little box trailer. If you tell it you just have a bike rack it probably doesn't inhibit the suspension.

I think on the L405 they've gone a bit further, and it actually senses and warns you of unusual movements in the trailer's load, so if you tell it you have a horse box the car knows what to expect from a horse box and can warn you if the horse collapses or something., then brings up the venture cam image to show you the inside of the horse box. I would assume it can do the same for a car transporter and basically warn you if it thinks the cars lashing straps are loose. Clever stuff.

Does the sat nav not just adjust the route allowing for the trailer , i.e. Avoiding low bridges, particularly narrow roads?

I'm going to have another look at mine at weekend. Seems like everyone's is slightly different

It might do but very few bridges would be low enough to warrant a re-route for what ever you're towing with a Range Rover (i mean a horse box is what 8-10 ft high?) and most satnavs can just differentiate between major roads and minor roads, some minor roads are really quite wide. So i'd think it was unlikely and probably just to do with the trailer stability assist or what ever they call it.

Yeah the camera system on mine can be setup for different trailers, caravans etc.
when you reverse it predicts the path of the trailer when you setup its length and number of axles.
Sat nav doesn't re route us. It's a LR nav so thinks up the weirdest route anyway.

It has the trailer stability assist where it brakes the car if the trailer starts to snake too. I don't get an indication inside but I think the L405 does have something inside saying its activating.

Looks like over the years there has been loads of updates and whether it involves ccf or not is MY dependant by the looks of things.

Looking at Davids car that MY should have the fogs and pdc disabled when connected to a trailer and should have the trailer light on dash.
My RRC even has trailer light on the dash. I'm surprised that a LR doesn't have the trailer light on there.

I think you're right, they've gradually added bits and pieces over the years. I think VW have a system that actually reverses the car and trailer combination automatically, similar to those automatic parallel parking systems you find on some city cars. -it's quite impressive really. I imagine we'll see that end up on a Land-Rover too if it isn't already.

Your Classic is presumably one with the Metro/Montego instrument cluster?

Something i noticed in the link i posted above, is that only a few countries (the UK being one of them) require a light check system for trailers. It's possible that if the wiring kit was a grey import intended for another market it doesn't activate the trailer attached light?

I'm the one with out the light And your right it is only the 2002-2005 that don't have them as far as I'm aware, for some reason BMW thought that they would be different and left it out, Ford replaced it on later models I wish that mine had the light, cos the LCM for the trailer is driving me nuts, every time I hitch on to a trailer with led's and put my foot on the brake "BONG,BONG" 'CHECK TRAILER LIGHTS' Shut the up Have you any idea just how many times I set that off towing from Malvern to Oxford? 1000 times too many Oh and just for good measure it goes off when you apply the brake and when you take your foot off as well  Yesterday I couldn't spell Engineer... Today I are one!
Inventor of the 'Guide-o-Matic automatic wheel alignment tool'
Former long term L322 owner, Up/Down graded to a Classic Tractor!

Ifor williams warn against LED lights, apparently you're lucky one some makes of car the lights wont work at all with LED's fitted.

^ I am not in a position to dictate what type of lights are fitted to the many different types of event trailer that I tow So I have just got to get on with it the best I can, trouble is I am now going deaf from having the stereo on too loud so that I can't hear the BONG  Yesterday I couldn't spell Engineer... Today I are one!
Inventor of the 'Guide-o-Matic automatic wheel alignment tool'
Former long term L322 owner, Up/Down graded to a Classic Tractor!

There are adaptors that go between the tow socket and plug to counteract the led bulb error messages. Unsure if the cost of them.
Swift caravan brought one out a couple of years ago as people were having issues with their leds on the caravans.

It's cheaper to replace the lights the last one I saw was £120 trade  Yesterday I couldn't spell Engineer... Today I are one!
Inventor of the 'Guide-o-Matic automatic wheel alignment tool'
Former long term L322 owner, Up/Down graded to a Classic Tractor!

It shouldn't be too difficult to make something, just a male/female lead with a box of resistors in the middle should do it.

Even a Y cable so you can plug in both the trailer and a trailer board with conventional bulbs (as a ballast) would probably do it.

I'm already there made an extension lead with 2 ballast resistors wired between earth and the indicators, stops the indicators doing a strobe impression, I'm now thinking about adding 1 to the brake wire too, just to stop the BONG!  Yesterday I couldn't spell Engineer... Today I are one!
Inventor of the 'Guide-o-Matic automatic wheel alignment tool'
Former long term L322 owner, Up/Down graded to a Classic Tractor!