What is this please ? Wiring Diagram for the components ?

[RAW]

So the Old Merc as I previously mentioned has some Spag Bol wiring going on, whilst a desire to completely strip out and start again is quite strong, costs, tools and location (on a slope) make doing any major work like this prohibitive.
Nonetheless, and with the help of members here notably @wildebus and @Squiffy , progress is slowly being made

In the picture below there is a switched relay and fuses for various appliances but not sure what the switch relay is for and could do with an original wiring diagram. It looks to me like the Part in the rear goes alongside the part in the front and they may have been put in together.
My son and I have been trying hard to un-entangle the Spaghetti Wiring with some success, whilst working hard yesterday we found the definitive proof of predecessor idiocy which was a 240V Double Socket wired to a 12V Supply !!

Pictures below and the one on the right is what I am trying to figure out, the relay maybe in the perspex box ?
Also Wiring diagrams for both would be good.

Front Leisure Controls and Fuses	Rear Leisure Fuses and Switch Relay ?

 

[wildebus]

sounds like fun!

going to throw in one comment about wiring. Not aimed specifically at yourself, but at anyone reading this .... try to avoid using domestic 240V flex cable for 12V circuits. I know technically it will work at lower amperages (and I do actually use it for one very specific purpose myself), it can lead to confusion at a later date when either you have forgotten what a cable is was for or if the vehicle is now owned/maintained by someone else.

Can't be sure of the relay purpose there.

 

[Squiffy]

What items are in the van that use heavy ampage ?, that must be your first aim to find out I.e. auto step, three way fridge or even are the internal lights halogen because if they are they would need a switched relay if using a minimal ampage classed light switch or does it have a duty water pump, my guess for the relay would be for the fridge. Does the relay activate when engine is started or does it activate at all when switching on various items, try tracing back the low tension side of the relay (The wire that activates the relay) and see where that voltage is supplied from. It is very difficult to say by just looking at the photo what is what but the size of fuses would give some indication. Phil

P.s Of course switching everything on then removing each fuse in turn will give you an indication too.

 

[RAW]

try to avoid using domestic 240V flex cable for 12V circuits. I know technically it will work at lower amperages (and I do actually use it for one very specific purpose myself), it can lead to confusion at a later date when either you have forgotten what a cable is was for or if the vehicle is now owned/maintained by someone else.

Can't be sure of the relay purpose there.

YES I echo that, 240V for 12V purposes is not a good idea. Would be interested in the 240V and what specifically you use it for?
Have installed all the cable you sent me (THANKS) and now have front batteries and rear batteries connected, all charging for the Split Charge circuit and all inc Vehicle charging from the Battery Charger and ALL batteries inc Vehicle charging from Solar - if doable with small panel!! Next thing is to increase solar to double output approx with the Flexi panels I am installing as non permanent, can be hung in other words. - More on that in another post. Also another fun part of the whole process has been getting the new stereo - well Android head unit in, and connecting that up to the old camera, which had power run from 240V Cable as well LOL

 

[RAW]

What items are in the van that use heavy ampage ?, that must be your first aim to find out I.e. auto step, three way fridge or even are the internal lights halogen because if they are they would need a switched relay if using a minimal ampage classed light switch or does it have a duty water pump, my guess for the relay would be for the fridge. Does the relay activate when engine is started or does it activate at all when switching on various items, try tracing back the low tension side of the relay (The wire that activates the relay) and see where that voltage is supplied from.

Ah right, that's useful - not started the vehicle to see if Relay does anything
High Amp - water pump
Fridge - Though looks like 12V supply to fridge is now disconnected from that Unit, as was troubleshooting that with you, and almost sorted it out now.
There is a Carver Cascade Water Heater that has a 12V Supply but think the 12V is only for the spark on the Gas Side rather than actually running a heating element.

Lights are all LED
There is a diesel heater, but doubt that would use much power

 

[wildebus]

YES I echo that, 240V for 12V purposes is not a good idea. Would be interested in the 240V and what specifically you use it for?
....

I use it when I want a three-core low-amperage cable to run between between two light switches (I have not found any 3-core DC-style cable and find it neater to use the 240V flex). You need the 3-core cable if you have lights you want to switch on and off from two different places (just like say a light in a house you switch from a hallway or a stairs landing). I fit a switch by the bed head and by the entrance door in a camper - saves having to get out of bed to turn the lights off

 

[wildebus]

.....Also another fun part of the whole process has been getting the new stereo - well Android head unit in, and connecting that up to the old camera, which had power run from 240V Cable as well LOL

I am assuming you have the radio on-off controlled by the ignition key?

 

[Deleted member 4404]

There is a diesel heater, but doubt that would use much power

It doesn't use much when running, but on start up and shut down it uses a lot

 

[RAW]

I am assuming you have the radio on-off controlled by the ignition key?

YES - Son kindly fitted that as he has more patience and more experience with stereo units having done a few in his cars LOL
The Reversing Camera we could not get to work at front of vehicle due to previous bad wiring so going to isolate that on rocker switch to do a security camera as well. Still looks like I need to resolve some Voltage loss on Leisure side.
Was isolating some items on a separate rear fuse board and there is definitely something weird going on as when wiring we can get an open circuit to ground on some of the previously wired & installed accessories. Fuseboard is

And what happened was the LED fault light lit up with no fuse on when son was holding positive and stood on ground with no shoes, odd

 

[wildebus]

YES - Son kindly fitted that as he has more patience and more experience with stereo units having done a few in his cars LOL
The Reversing Camera we could not get to work at front of vehicle due to previous bad wiring so going to isolate that on rocker switch to do a security camera as well. Still looks like I need to resolve some Voltage loss on Leisure side.
Was isolating some items on a separate rear fuse board and there is definitely something weird going on as when wiring we can get an open circuit to ground on some of the previously wired & installed accessories. Fuseboard is
View attachment 2461
And what happened was the LED fault light lit up with no fuse on when son was holding positive and stood on ground with no shoes, odd

Ref the fuse light ... that is spot on behaviour. that is how the blown fuse light works. He was completing the circuit though his body.

Ref the radio ... I'll send you a radio kit that lets you choose to have it come on with the key or without

 

[RAW]

ef the fuse light ... that is spot on behaviour. that is how the blown fuse light works.

Ah yes, me getting confused. That fuse is powering something switchable and does not light when off and no fuse in board. The other fuses are powering always on devices so LEDs will light when fuses removed.

 

[Nabsim]

I would have thought the main issue (I dont think problem is right) using household 240v cable is the bulk. Automotive thin wall cable is much thinner for a given rating. What could be a problem is if you use 240v single core cable, thats not recommended for vehicles although it will work until such time it fractures.

It wouldnt bother me using 3 core flex if I needed 3 cores but I am not electrician

I think I have seen 3 core trailer cable Dave if you did particularly want to use automotive, not checked but thought it was at eithe Vehicle Wiring Products or 12v Planet when I was looked for a 7 or 9 core last year.

 

[wildebus]

I'll have a look. Don't use much of it and it is the same cable in terms of copper, but it is the potential for confusion down the line - and the bulk is a factor if used extensively, as you say.