I didn't know Renault made Megane trailers let alone trailers with headlights. Are you sure you know what vehicle you have because your question is in the trailer section of Vehicles main heading.
Asking the garage where you bought it would be the most commonsense thing to do. Nothing to be ashamed of I've had a Peugeot for 7yrs from new and I still don't know how to turn off the service warning display it now show 3,000 miles over service mileage and its had 4 services. I look in the engine compartment then shut it wouldn't try touching it. Not like the old cars where a pair of tights would serve as a temp: fan belt.
Bob
September 2010