Just put my camper on to take it for a drive and the brake lights don't work, tried the box trailer to check and those brake lights don't work either. Tried the missus car and the trailer lights worked.

I've unplugged the connections on the car cleaned and replaced and still nothing tested with a multi and it read 13.5 on the breake light pin so I'm at a loss.

If the pin is getting the power and there isn't anything wrong with the trailer what could be going wrong?

Thanks in advance

Warwick