Although the RR (2009MY with digital dash) has presumably had the hitch and 13-pin socket from new, it’s also clearly never been used. I’ve had to find time to soak and free off the three balls of the hitch lock to allow me to get it up into the adaptor enough to let it latch and lock. And at last, today, I reversed up to my Ifor Williams, hitched, connected and… nothing. No lights at all. Plus the RR clearly wasn’t seeing it either as it objected to the trailer being there when in reverse.

The bike carrier with its built-in LED lighting board had the same outcome.

The CCF shows the car is aware that it has the hitch with a 13-pin socket. I’ve checked in the rear o/s area the only two fuses in the board that show a trailer on them (Nos. 8 and 9) and they’re both good and relay No.3 is present. But where next?

(If anyone suggests I need to look at the passenger fuse box I shall have a spasm – my lower glove box stopped opening last week. Because it just would. Where do I start with that before I can start with the trailer socket?)

Click image to enlarge

Time to get that spasm warmed up, thats where the fuses are, on my 2011 322 they were all blown. BMW i3 Electric Car
2012 Full Fat RR 4.4 TDV8 (now gone)
2006 VW Touareg 3.0 TDi V6

In desperation, I firmly wedged both kneews and, magically, the catch released. After some rearrangement of contents, it's now fine. Great!

So, on the the fuses... also all fine. Not great!

An hour later the reason for no trailer lighting was discovered. Delving around the spare wheel under things that have been there since before I bought it a couple of weeks ago and things I've put in there since, we discovered a plug coupler. Well, half a plug coupler. Then we discovered the other half. Once they were re-introduced to each other, the tester plugged into the 13-pin socket lit up exactly as it should.

Haha, I was going to ask you yesterday if you had the connector checked but thought, silly me, that's most likely the first thing he checked.
At least it's solved now.