added led panel to dome light and on/off

What I am looking to do is install a little 16-led panel to the back of my wife's 08 focus. The car has no light in the back and it sucks so I want to install some light.

I would like to hook it to the dome circuit so it comes on when the doors open but also be able to turn it on and off when the doors are closed from a switch. I am having a hard time getting this to work. I am thinking I will need a 3-way toggle? Then it’s just figuring out how to wire it the way I need it, the led is just +/- but how would I wire the whole thing together? I know this sounds simple but I have tried to search the web and nothing is really clicking for me to understand you know what I mean.

Any help would be greatly appreciated.

Thanks

Wad

Thanks for the reply, now I need to go get a switch.  Thanks for the help.

If it's a boot/trunk light or otherwise easy to miss, consider that it might be left ON by accident.

Another problem is that you'll be connecting it in parallel with the existing dome light, hence you'll also be turning the dome light on.

Rockers are fine provided you realise center is off (for most 3-position rockers).

Noting that your added light/LED will or could have its own +12V supply, its -ve end could simply connect to the -ve end of the dome light and have an on-off switch to GND to turn it on.
Hence it will be on with the doors (open) or when your added switch is on.   
To prevent your switch also turning on the dome, you could fit a diode (between your switch and the dome, line end towards the dome).

And if your door switches do not have isolating diodes, your 'dome connection' could simply be any of those door switches.
IE - traditionally door switches were simply paralleled for a single dome light. Diodes might be added if other circuits also use door switches - eg, alarms, remote starts - or for other 'unique for door' features.
An example of the latter is if an in-door light or puddle light or door-status dash light or alarm only activates for that door.
Another is my headlight warning buzzer which only activates with (headlight or parker/taillight) light on AND the driver's door open, but NOT passenger door. Hence I fitted a diode from each(?) switch and hence the passenger door switch wire can no longer tell if the driver door switch is on (they used to be connected in parallel).


Simple circuits like this are so easy aren't they? (NOT!!)

If you have a plain basic system it should be easy.
It's if it has automated dome light dimming or door monitoring etc that it can get complicated, tho worst case usually involves a separate +12V supply or a diode and wire to each door switch respectively. Usually...

The vehicle's wiring diagram would be best unless it it known that it is GND switched and has no dimming or diodes (ie, no individual door monitoring).

And we should probably add the dome light to my diagram. (The round with cross bulb shown is really your added light. It doesn't show the existing dome light nor its wiring.)

Ok, I am still not getting it.

I bought a on-off-on switch from the auto part store.  It has ACC On Source and ACC On (3 prongs only)

My LED has + - with the resitor on board

My dome light has 3 wires.

With out the switch I can move the + and - for the led around the dome light connetor and get it to come on when the door opens and I can move it around to only come on if I turn on the switch by the headligh swtich.  I can also move it around to stay on all the time. 

I am having a hard time installing the switch I bought to the exsting dome wiring to get the new LED to work.  i think I am either totally not getting this or it is not going to work. 

You guys are way smarter than me and I am sure its just knowing which wire needs to go where but I cant figure it out as soon as I add my new switch.

Thanks

Wad

How's the following which shows the new trunk LEDs (3 diodes/LEDs) wired into the exiting dome & switch (round-crossed & dome selector switch. It's from led triggered by dome light and on/off/on & new dome lights with new switch wiring if they add more info.

Note however that it assumes your existing dome uses ground switching - ie, one side is always hot = +12V.
The fact that your headlight switch can also turn on the dome could mean +12V switching, tho even door switches can to that.




PS - An '03 Focus diagram I have shows GND switching albeit thru a "Generic Electronic Module (GEM)".

Thanks for your help, but I decided to just tap into dome light harness before the domelight connector and ran it  way.  So, it comes on when the doors open and also when I flip the switch near the headlight.  Not a big deal after thinking about it, its such a small car that if we need the front lit we can hit the dome light itself and if the kids need light I can flip the switch for then new LED in the back.