In 2015 I had a specialist trailer company fit a 13pin connector to my motor. The flicking indicator trailer lamp disappeared. I queried it and was told the law only states audible or visible monitoring. It never occoured to me that we were talking P38 electrics at the time. I don't suppose, given the pain I've suffered hitherto, that there's anything that doesn't matter but nothing horrible's happened yet (like when I upgraded the satellite receiver to DVD or switched the HEVAC controller). The old double sockets showed the blinking trailer icon. Noteably all the lamps on the caravan are LED. Resistance? Wattage? I've just tested and renewed all lamps on the binnacle. Trivial, I know, but when you're as paranoid as me evrything is magnified.