I have a face lifted L405 model year 2018.
We are shortly getting a new caravan and the supplier has advised that some vehicle show a fault light on the dash when connected to the led type bulbs.
Does anyone know if this is going to be a problem?
The Range Rover has a great deal of led lights anyway.

Not sure mate, but check in plenty of time before you tow the van, my neighbour bought a new RR sport, and he couldn’t get the road lights on his, not so old Bailey van, to work at all. Took ages for the dealership to figure out what the problem was, too much power going through if I remember correctly.
Can’t see you having a problem.
Not sure if that helps🥴

It depends on what it expects to see in terms of load from the trailer lights. Worst case scenario is you need to add resistors to the caravan light circuits to provide additional load. Easy to do and usually convenient access in a seat locker in the caravan.
On some vehicles you need to disable cold testing of bulbs, this is where a very short pulse of power is applied to the circuit, if the car doesnt see current flow it detects a bulb failure. With a normal bulb the pulse is so short it doesnt illuminate, with LED's they flicker. I dont know if the Range Rover has form of testing, my VW Touareg did. BMW i3 Electric Car
2012 Full Fat RR 4.4 TDV8 (now gone)
2006 VW Touareg 3.0 TDi V6

I’d suggest you get in touch with Sargent. I think their website is www.sargentltd.co.uk . They make about four different types of resistor box, depending which car and which caravan. I found their helpline phone number service massively helpful…….

………unlike the caravan dealer we spent £26k with for a new caravan who didn’t give two hoots about road safety 🙈

It’s a much earlier car, but we had big issues towing a new 2018 caravan with our 2004 L322. The lights worked albeit the “tick” the indicator made in the car was faster than normal and an error message showed. The dealer said “your lights work, everything is fine”.

On the first trip with it we had a huge moment on a dual carriageway at 60mph. Terrifying. I have my HGV licence and grew up on farms so had towed all sorts but this was a new one on me. The caravan dealer was useless but somebody said to me that because of the LED caravan lights, the L322 doesn’t know it’s towing. So the L322 doesn’t activate its towing software. And for us, the L322 had done its normal lowering by an inch at 60mph with the caravan attached. Hence a big instability moment. We then got the right box fitted to solve the problem. It was about £40 iirc.

In a nutshell, you are absolutely right to take this kind of issue very seriously. 2004 L322 4.4 V8 Vogue Bonatti Grey
(205,500 miles and counting.......)

Sorry dentaldave, I should also have said that a good, easy check if your car knows it is towing is check the rear parking sensors automatically stop working when the towing electrics are plugged in.

If your parking sensors at the back still work (ie go off when you walk by the rear bumper) when the tow electrics are connected, I’d suggest you‘be got a potentially serious issue to resolve before towing with that car and caravan. 2004 L322 4.4 V8 Vogue Bonatti Grey
(205,500 miles and counting.......)

+1 for Sargent we needed a extra “box” fitted to the caravan for both the L322 and L405. Sold - Bell a 2015 MY16 Loire Blue Autobiography 4.4 SDV8
Previously George a 2007 MY07 Java Black VSE 3.6 TDV8
Previously a 04 MY04 Defender 90

Sargeant box is quick and convenient but expensive compared to just purchasing the resistors do do the same job. It depends how much DIY youre happy to do. BMW i3 Electric Car
2012 Full Fat RR 4.4 TDV8 (now gone)
2006 VW Touareg 3.0 TDi V6

Ours was £32 looking at the invoice. It comes with the patch leads and a nice aluminium casing that looks OEM in the van next to the original. It’s plug and play no need to cut or solder anything. In our case it wasn’t worth the hassle and especially as the van was under warranty at the time. Sold - Bell a 2015 MY16 Loire Blue Autobiography 4.4 SDV8
Previously George a 2007 MY07 Java Black VSE 3.6 TDV8
Previously a 04 MY04 Defender 90

That seems a much better price than they used to charge. BMW i3 Electric Car
2012 Full Fat RR 4.4 TDV8 (now gone)
2006 VW Touareg 3.0 TDi V6

I've just fitted that box to my 2019 Swift and it has fixed the speed of the indicators, and the trailer light on the dash comes on now but the Range Rover still says there's an issue with the trailer lights.

Hopefully that's a case of "the dash light is on so it'll do". The only symptom I can see is every now and again there's double flash with the hazards on. Which I suppose is going to be a frequent occurrence with a Range Rover.