Constant 12V supply to rear?

My local mechanic showed me the new LED lights he'd installed in his amazingly customised 90 the other day. I asked if he'd run new wiring with an inline fuse from the main battery to power the lights, but he said that there was a permanent 12V supply (without the ignition being on) going to the rear, which he just spliced into. No fuse needed because the LED lights required so little amperage, so it was just a matter of splicing in and adding a rocker switch...no fuse or melting wires to worry about.

So, does anyone know what colour wire this constant 12V supply would most likely be? And would it be on the offside or nearside do you think?

I was hoping to avoid probing with the multi-meter you see.

the wire he used will most likly be fused some where along the line as its a standard item

discomark10 said:

the wire he used will most likly be fused some where along the line as its a standard item

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I've just used a multi-meter to test all wires behind the rear offside panel, but no 12V reading. Damn, I thought I would avoid running a new line (with inline fuse) from the battery. Any workarounds?

Actully, would it read 12V if no device was requesting power? How do you test to see if a vacant line is actually available to serve power?

what about the trailer wires?

discomark10 said:

what about the trailer wires?

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Wouldn't the ignition need to be on for the trailer wires to be live?

i would say it might have constant live if you were to use a caravan possibly

discomark10 said:

i would say it might have constant live if you were to use a caravan possibly

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Any idea how to test for constant live using a multi-meter?

just have the iginiton off and test for 12v

discomark10 said:

just have the iginiton off and test for 12v

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Tried that and no joy. Looks like I'll be running a new line. May as well add a 4-way fuse box too.

Under the Landy with cable ties again...bugger!

failing that what about looking for a wiring diagram?

or might be a live to rear interior lights/boot light.

I believe that the wire in question should be purple.

discomark10 said:

failing that what about looking for a wiring diagram?

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Such diagrams drive me crazy. All those lines and symbols.

I have an Anderson plug with wires the same as the battery cables,at the back
of my 110,and plan to get some extra plugs to fit to accessories.
But, I want to run another cable to the back which would be live,and also
attached to a split charge big 110 amp liesurebattery
so I can run interior lights,tv etc.
I am in the middle of converting my 110 hardtop to a camper.
Can you say what size cable I would use,and inline fuse please.

Ham Salad said:

I have an Anderson plug with wires the same as the battery cables,at the back
of my 110,and plan to get some extra plugs to fit to accessories.
But, I want to run another cable to the back which would be live,and also
attached to a split charge big 110 amp liesurebattery
so I can run interior lights,tv etc.
I am in the middle of converting my 110 hardtop to a camper.
Can you say what size cable I would use,and inline fuse please.

Click to expand...

well, work out the max watts at 12v you would need to be running at once then it can be worked out

If you get underneath the rear cross member there are usually one or two 'unconnected' wires there - no idea if permanent live or not

ratty said:

I believe that the wire in question should be purple.

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It should indeed.

It's a fused live for the rear interior light.

I wouldn't go drawing too much current through it though. Im pretty sure that is quite a small diameter wire if I remember correctly.