Using both starter battery and leisure battery to power rear lights. Anyone successfully done this? Help appreciated

[PrinceAdam1978]

Hey guys,

Both my friend and I are upgrading and converting our t6 vans, and we ran into what seemed an inevitable problem re: usage of the lights

We wanted to use both the door sensor / leisure circuit to make use of the lighting but I think we have hit a wall.

Has anyone successfully installed down lights in the rear and use a rocker switch etc to isolate one from the other so on a three way rocker (position 1, 0, 2) we can move from courtesy lighting to full leisure power?

Tried trawling through but I’ve struggled.

Many thanks for your help and advice

 

[Howzat]

I did the 3 way rocker. 1 uses the +ve (switched earth spliced from the existing lights) so the lights come on with the door opening. 0 is off (unwired). 2 uses an earth to the body for constant power. Fed the live direct from the leisure battery.

 

[Absolut5]

As above , 1 uses the brown/red from original lighting circuit ,

 

[PrinceAdam1978]

I did the 3 way rocker. 1 uses the +ve (switched earth spliced from the existing lights) so the lights come on with the door opening. 0 is off (unwired). 2 uses an earth to the body for constant power. Fed the live direct from the leisure battery.

Thanks pal. So your method still sends signal to the bcm?

So +ve red from leisure battery to rocker #2
Switched -ve from the loom to the #1 position, but that means there’s no return?

Can I be incredibly stupid and ask how u did it via a diagram?

 

[Howzat]

Thanks pal. So your method still sends signal to the bcm?

So +ve red from leisure battery to rocker #2
Switched -ve from the loom to the #1 position, but that means there’s no return?

Can I be incredibly stupid and ask how u did it via a diagram?

Cant draw.
And you are NOT wiring anything from the battery to the toggle switch! That wont end well.

I'll try and explain further,

1. Unclip one of the OEM lights in the roof. Look for the brown/red wire as mentioned by @Absolut5. Now remove some insulation and connect a NEW wire to the bared wire. Run this new wire to the toggle connector for the 1 position.
2. Get another new wire and connect this to the van body so you have a permanent earth. There's an earth nut/bolt at the back behing the internal side panel on the nearside but you can easily connect this to any bare metal on the van. Once this is connected run the other end to the toggle switch 2.
3. Run another new wire from the centre terminal (0) on the toggle switch to the earth wire on your lights.

That's the toggle wired up.

Now run another new cable (with an inline fuse for safety at the battery end) from the leisure battery +terminal DIRECTLY to the + wire (usually red) on your new lights.

What's this doing?
When you splice into the existing OEM wiring you are creating a switched EARTH which is controlled by the BCM. This will switch on the new lights when ANY door is opened and will turn them off when all doors are closed OR after 10 minutes if the doors remain open.
The other wire to the bodywork creates a permanent EARTH. This will allow the lights to stay on forever until the battery runs out.
So both new wires are EARTH connections.

How this works.
Switch the toggle to position 1 (fully left) and this connects the toggle terminal 1 (BCM earth) to the toggle terminal 0 (new lights earth).
Switch the toggle to 2 (fully right) and this connects the toggle terminal 2 (VAN earth) to the toggle terminal 0 (new lights earth).
When switched to the center position it means the switch isn't connecting to any of your new wires so the light stays off.

 

[Salty Spuds]

Starter battery is sacred & has one purpose. Personally I’d run some separate lights exclusively of the LB.
Just my 2 penneth

 

[Absolut5]

Thanks pal. So your method still sends signal to the bcm?

So +ve red from leisure battery to rocker #2
Switched -ve from the loom to the #1 position, but that means there’s no return?

Can I be incredibly stupid and ask how u did it via a diagram?

Simple explanation

On/off/on switch,
Pin 1- brown/red from Oe lights
Pin 2 - neg side of down lights
Pin 3 - ground

Down lights + straight to leisure battery with in line fuse

 

[PrinceAdam1978]

@Howzat & @Absolut5

Thanks so much for your help!

Followed what you said and both mine and my buddy’s van now work as we wanted and how we expected.

Three way rocker; I / O / II

Position I - Cabin/BCM Circuit
Position O - Off Completely
Position II - On, using Leisure Battery

On with the rest of the conversions!!