Interior light control

[BaxNy65]

I have a 78 F150 and I'm redoing the dash components. I updated the instrument cluster with lights and a printed circuit board. My question is about the headlight switch. When the truck is running I can turn on the headlights, but to get the instrument lights I have to turn the knob all the way to the left and past the click. I thought that the far left past the click was just for the dome light, and when right of the click the cluster would still be lit and you could dim the instrument cluster. I can't find anywhere about the control.
Thanks

 

[Fellro]

You are correct, the switch past the click is for the dome light. Seems the wiring off the light switch may be pinned incorrectly.