Door Jamb switch wire - where does it travel to?

[blindbug]

I’m trying to fix my under-dash courtesy light so that it comes on when the door is opened. I’ve pulled the jamb switch from the drivers door (I don’t have one in the passenger jamb). There is an orangish wire coming out of the switch, and only that one wire. It travels up and then through the kickpanel area and around to beside the fuse block where it has a terminal and hooks up to another wire which looks like it is going to the back of the fuse block. You can see it to the left in the picture.

I’ve manually shorted he wire that attached to the switch against the body, but that doesn’t seem to activate my under dash light, which is not what I expected. My understanding is that the switch just grounds the light also that it can light up.

Any help on what I can check or if I’m just chasing a lame goose is appreciated.

1986 Chevy C10 Custom Deluxe. No dome light, no passenger jamb switch.