DLR and trailer issues

I will post this in the technical session but also here in case any know?

I have an issue with my trailer. All is working electrically except the DLR function is not putting the lights on the trailer. If I go to normal lights (not auto and day lights) the lights come on the trailer. The indicators, brakes, dipped rear lights, rear fogs all work. I also checked the electrical connections on the trailer and all are well.

I am not sure but wonder whether as the car are LED and the trailer old style bulbs could it be that the current to the trailer connection is insufficient?

Anybody had this issue?

Thanks in advance.

Thanks for your replies. Yes it's an Audi factory fitted option, ordered with the car.

I think the issue might be the trailer brake light shares the rear lights. What I mean is that the bulb has 2 filaments. Either illuminate depending on whether you have the lights on or not. I had double checked again and this time the car accepted there were no bulbs out on the trailer. Then I tried it again and it said the brake lights were out! Therefore I'm wondering if this shared bulb is what is causing the car to see a fault?

I contacted Ifor Williams for help but I don't expect much help there.

I had heard that some types of LED lights on trailers could fool the car into thinking there was an issue but on the older filament type lights I had thought all was okay.

More investigation needed. I can see Audi saying it is the trailer at fault or something of that sort so I'll try to do some legwork first.