Just bought a Sankey widetrack trailer - was 23KE51 in service, which I think indicates c.1985. All the lights work as per spec except the two white lamps on the front corners. I'd expect them to come on with the vehicle sidelights, but they do nothing at all.
The only wiring diagram I can find is for the earlier narrowtrack trailer (probably much the same) but I can't work out from this where these two lamps get their power. Are they wired into the tail light circuit or elsewhere?