Problem with internal electrics

Hi
Can anyone help me please?
We have a 1986 T25 Autosleeper, and yesterday fitted a new leisure battery. Nothing behind the cab seats worked, no lights, water pump etc.
So today, we bought a new earth lead and fitted that, in case the earth was dodgy. Still nothing. 
I tried turning the ignition on, and tried the lights, water pump etc, and they worked, what’s going on? Both the leisure battery and the camper battery are fully charged. Obviously, we need to sort it before we can use the camper again. Incidentally, everything was working ok, prior to replacing the leisure battery, but because we hadn’t used the camper because of lockdown, we thought we would replace the leisure battery with a new one, and are now experiencing this problem. Please help.
Thanks

One of the problems on a van of that age is knowing how A/S wired things up that far back. One thing that you should check - if you haven't already - is the main inline fuse in the positive connection to the leisure battery. There will always be one, but you may have to search a bit to find it.

The reason that everything starts working when the ignition is on is ~probably~ that the split charge circuit that charges the leisure battery from the alternator was simpler in those days. More recent installations only connect this circuit when the engine is running, but it sounds as though yours may be wired in a simpler manner.

Hi

It seems that up until 1988 AS didn’t include a wiring diagram in the manual.

1987 Manual (no wiring diagram) here:
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1988 manual with wiring diagram here:
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Nevertheless, things changed much more slowly in those days so the 1988 diagram probably won’t be far out.

Roopert wrote: More recent installations only connect this circuit when the engine is running, but it sounds as though yours may be wired in a simpler manner.

Looking at the diagram, the split charge relay was indeed operated from the ignition switch and both batteries should connect both batteries together, so the fact that everything works when the ignition switch is on strongly points to the leisure battery simply not being connected.

Why did you replace the earth lead, presumably there was something about it that didn’t look right?   Just to be sure you could try connecting the negative terminal to another part of the bodywork with something like a jump lead.

If that doesn’t work check that the red lead is connected tightly and try and follow it to whatever it’s connected to. Hopefully you’ll be able to see the problem.
Even if you’re not good with electrics it’s still worth getting hold of a cheap multimeter.  Basic checks really are very easy and there a plenty of folk on here that can tell you how to use it.

Brod

Thanks for that. We tried connecting the negative terminal to another area of the van, and still nothing. We tried chasing the positive back, and checked all the fuses and still nothing, so we are stumped.
We are going to ask an auto electrician for help, as we are completely baffled. 
But thanks for the advice

Be handy if you know someone with a multimeter who would likely quickly find your problem. Having replaced battery and earth lead defect appears to be in positive line.  You say all fuse have been checked,it is very unlikely all circuit fuses have gone at same time to de power all circuits so it would seem the likely cause is main battery fuse on positive line blown,(possibly when changing battery) or defective cable or connection at positive terminal. Hopefully not a major fault and you will soon be up and ready to use your van again.