hello, I am trying to fix my broken glove box light.

the switch does not receive 12V on ignition like it should. there is an aftermarket head unit installed.

I have searched and ran continuity tests all over the wires in the area that goes to the cigarette lighter and the radio, but I cannot find which wire the switch is powered from.

does anyone know off the top of their head which wire it is? i am about to give up and solder a new wire to the cigarette lighter 12V.