interior lighting woes

[getunder]

Tried the interior lighting after not using it this winter. None of the interior lights would work.
1985 van. "Devon" Elecrical unit.
1.I ran a separate earth wire to the battery and checked input wires behind light units with a continuity lamp. Nothing.
2. I checked the 35 amp fuse next to the battery. OK
3. I tried the Fridge switch on the electical unit with the engine running and it worked. The red light switch illuminated.
4. I checked the supply fuses in the unit and all O.K.
5. I tried the water pump wires with it turned on but Zilch. But it hasn't been used for years anyway.No supply to wires to pump unit in water container.
6. I have an interior wiring diagram supplied with the van and checked unit output on the No.5 socket which supplies interior light - nothing.
7. I checked the other socket outputs from the unit and nothing
I guess this leaves the unit itself unless anyone has other ideas. Has anyone had problems with the unit before ?

[T'Onion]

Is your leisure battery charged ? check the voltage
does anything work when the engine is running ? again check the voltage
If there is no difference between the engine running and not then it could be the split charger
Have you tried plugging the van in to the mains ,assuming that the 'devon' has a battery charger and then trying the leisure stuff

ps the fridge should be on a different relay to the leisure battery

pps join the club

[getunder]

Thanks for tips to try T'onions. So far: Found the 15 amp fuse in the split charger relay was burned out. Replaced it - still no interior lights. New fuse still intact.The leisure and main batteries had been charged externally a couple of times this winter and a direct wire from the leisure battery showed that the lights worked. Also tried light direct earth to battery.No dice.Tried it with engine running-no dice.Tried it on mains- no dice. The three lights on the "plug in" mains safety tester all lit up. Took Unit off and found a Relay in it, wired up to the illuminated Fridge switch and to the Fridge itself presumably plus two other smaller wires coming out of Relay. Work In progress -leisure battery on fast charge. Should be enough extra in it in a few hours to try again. What a wonderful life

[getunder]

Progress report. Leisure Battery well charged but still no interior light. Seem to have covered all the bases. Might have another look tomorrow otherwise will give up and use my 24 LED inspection light or torches instead for the amount I use light. You cannot trace any wires through except by dismantling the entire interior Grrrrr.I don't like being beat but have been working on the van continuously since mid January ,one darned thing after another, as much as flesh and blood can stand