hm... this is confusing.... maybe the dimmer is messed up have you tryed checking out that area to make sure nothing is stuck?

 

have just disconnected the light switch and all the lights go to fail safe and stay on

just checked the fuse No. and its 23 i've pulled not 18 !

 

One of the doors must have a faulty switch that tells it to turn the lights off. You've covered all the basis, I that's pretty much all that's left.

 

I have the same problem, where do you find the door switch in a 2004 durango

 

If the door switch was faulty wouldn't you have a door ajar light on aswell?... I personally would check the dimmer switch and the wires leading to and from it...

 

are you sure you went to the power side after the switch ?? just does not make sence if you turn off the switch lights should go out ?? sounds like you went to a constant power source ???
Got me ??

 

If I could make a suggestion. Because the interior lights will work without the key on,it sounds like you have completed a ground path in your wiring. Try this and it may solve your problem. It is a little work but well worth it it if it helps. Under the dash near the emergency brake is a large connector with 74 wires in it. This connector has a bolt in the middle of it. Look for the wire in location # 19. It is a black wire with a yellor stripe on it. This is the factory clearance positive wire. Use a test light and see if you have power at this wire with the headlight switch on. If you do, re-run your power wire and tie into this wire.... Hope this helps....