Hyundai Tucson trailer wiring

I'd have thought that this socket would be an ideal source.

newshound used his keyboard to write :

10amps rating from a ciggy lighter feed might be marginal, depending on how many lights are on the trailer, usually these things need a 20amp supply. If the 10amp is via a 10amp rated cable, volts drop also might also prove to be an issue.

If *everything* (2 x 6W tail, 2 x 21w stop, 2 x 21w hazard, 1 x 21w fog) were on at the same time, that would be 117 watts - which is getting close to 10 amps. But that would be an absolutely worst case and would be extremely unlikely to occur in practice. I accept that there's not much in hand if a subsequent owner decides to tow something else - with a lot more lights. Are there any legal reasons for doing it 'properly'? For example, could I have a problem with an MOT test when the car needs one in a couple of years?

Would fitting LED lamps on the trailer make it a non-criminal bodge (so long as the OP remembers not to borrow another trailer)?

I don't know if it'd be lawful but I can't see a current (sic) MoT picking it up with a 7 pin socket unless the tester can see just where you've sourced the power:

Roger Mills submitted this idea :

If it works, then probably not, but for the sake of a bit of cable and a small amount of time, why not do it properly?

Most modern vehicles have a fuse link somewhere, set aside specially for a trailer 12v supply. You only need find it, and run a cable from there to the rear.

Yes, I'd prefer to. But one lot of instructions I've seen for installing a dedicated wiring kit seem to suggest that you need to remove a hell of a lot of trim in order to run the cable to the front. I'm not 100% confident that it can be done non-destructively.

Indeed. Can any of you with knowledge of this vehicle give me a clue as to where to look?

Worth checking the rating of the socket, I thought many of them would supply more than that.

Every one I have ever seen is protected by a 10A fuse.

Chris

So effectively, all you need is the lights?

I'd be surprised if the existing wiring couldn't cope with LED based units.

Problem might be, of course, warning of bulb failure due to the different load.

It happens that Roger Mills formulated :

Likely there will be two fuse panels, one in the cabin, one in the engine compartment. Look in those (probably engine one), for a trailer/caravan symbol. That should be the correct fuse for the job.

Yes, indeed. Mine is labelled 180 watts - which implies 15 amps.

Thanks - I'll have a look. But, if that is the case, connecting to that would be no easier than connecting directly to the battery via an inline fuse. I was hoping for something nearer the back!

Problem is that my trailer - and the lighting board I use when carrying bikes - both have conventional tungsten bulbs. Are there LED equivalents which will plug into the same sockets?

[...]

Yep.

Chris

Not sure. Many replacements include a resistor or whatever to fool the bulb failure unit. Not exactly the best way of doing things. A decent LED should use about 1/10th of the current of the rather inefficient tungsten tail light bulbs, and I'd expect the wiring to not notice that.

The high current feed to a trailer socket is to run things inside a caravan.

Many say CANbus compatible. Do they actually draw only the low current the LED needs - or increase it artificially to 'look' like a tungsten?

The aftermarket headlight LEDS I have on my old car have an external unit for bulb failure unit fooling - and that gets very hot. But it's before CANbus.

It happens that Roger Mills formulated :

Always best to do things the way the manufacturer intended. It might even be, that the manufacturer actually ran the feed wire to the rear.

Roger Mills explained :

Yes, take a look on Ebay. For a trailer which maybe lacks Can-Bus monitoring, you should be able just use none Can-Bus LED's.