Can anyone help me with an electrical problem in our 1988 Maramu 46 #240.

All the lights in the aft cabin have failed.  We checked all the bulbs,
of course! We have established that the problem is with the positive
cable as we have checked the negative (ground) cable and it has
continuity. 
We've established that, if we get power to any one of the light
fittings, all will then work. 

We can't work out how the positive cable gets from the circuit breaker
on the 12v panel and the first light in the aft cabin.  All the cables
are hidden. 

If anyone has had this problem before or has access to a cable routing
diagram, I'd be glad of your experience. 

Kind regards

Graham

Jamesby
Maramu 46 #240