Dome light not working when doors open, routing new wire?

[Anzezaf]

My dome light doesn't work when my doors are open, but if i put the switch to the ON position it works just fine.
The door-dependent "mode" doesn't work at all, even if i open just one door, both, or just the passenger side..

The door jamb switches work fine, because i get an indicator light on my gauge cluster when my doors open.
I checked all the fuses, they're ok. I also checked for the switched ground on the dome light connector black-white wire, and it's not grounded at all, it has 10V on it and it doesn't matter if my doors are open or not. So I'm fairly sure its that damned multiplexer unit that's faulty and I have no way of replacing it.

First I would like to try to route a new wire from the door jamb switch directly to the dome light connector, but I cannot find any good information about how to do it. Any ideas? Which panels need removing, where's the harness for the light, which wire to tap etc.

[Samiya85]

Could be the light that is faulty

[Anzezaf]

Nope, it was the multiplexer unit, or something similar to that.
I just routed new wires, one on the passenger side (I have left hand drive lude) from the door jamb switch wire (green+orangebrownish) in the right side of the passenger footwell behind the cover panel up thru the right side corner of the dash and up the pillar to the white-black wire for the light's door-switched ground.

The driver's side was easier, I just routed it from the jamb switch, up behind the seatbelt panels, up to the roof and directly to the light.

Took about two-three hours since I was discovering everything for the 1st time